[sdks] Source drop from xamarin/mono-sdks (#5876)

```
commit dcd3ed4930fbfa19df1a34c17bc17f5a57badb83
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Apr 6 15:53:36 2017 -0700

    switch mono to 2017-04.

 external/mono | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

commit cbff024be0d2ed30efda0ee228c339e4e2dce866
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Apr 6 15:53:13 2017 -0700

    Update readme with xtc specifics.

 README.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

commit b385e6ce4ee7ffb92cdb39cdf8bbdb82355d909f
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Apr 6 15:34:18 2017 -0700

    Add makefile to build & submit to xtc.

 android/xtc/Makefile | 7 +++++++
 1 file changed, 7 insertions(+)

commit 09ca3773ac25d8415c537f063d057aa471bb1eae
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Apr 6 15:08:29 2017 -0700

    UITest based runner.

 android/xtc/RuntimeTests.csproj | 43 +++++++++++++++++++++
 android/xtc/RuntimeTests.sln    | 17 +++++++++
 android/xtc/Tests.cs            | 84 +++++++++++++++++++++++++++++++++++++++++
 android/xtc/packages.config     |  5 +++
 4 files changed, 149 insertions(+)

commit bc20ebfeb58ee9d876e2f675651bdb9afa07fdeb
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Apr 6 15:05:39 2017 -0700

    Finish x86 support.

 android/Makefile           | 4 ++++
 android/jni/Application.mk | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

commit dcec00c4ef9240324ef3c4b9a4d5ab7c670c1984
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Apr 6 13:49:55 2017 -0700

    Add new redeploy target plus fix bcl staging.

 android/Makefile         | 4 ++++
 android/managed/Makefile | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

commit 5d6db27c2a3039271138f9f8c58a72262211793d
Author: Bernhard Urban <bernhard.urban@xamarin.com>
Date:   Thu Mar 30 18:26:24 2017 -0400

    [readme] add todo item for android

 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

commit 9ebd7bed3a5e66ccae2819e4c1045a1714a4274b
Author: Bernhard Urban <bernhard.urban@xamarin.com>
Date:   Thu Mar 30 17:39:49 2017 -0400

    fix default make target

 Makefile | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

commit f307dd3ef39733f528f1ef816741d2a9f4017f7a
Author: Bernhard Urban <bernhard.urban@xamarin.com>
Date:   Thu Mar 30 17:37:11 2017 -0400

    [sdks] use $(NDK_DIR) from paths.mk

 sdks/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

commit 83f470fcd7b039fd7945ec939c314bc18d2829ad
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Mar 30 16:58:45 2017 -0400

    More todos

 README.md | 1 +
 1 file changed, 1 insertion(+)

commit d5a3d38a848860f5c4ba320c0ca6d26d52eff635
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Mar 30 16:58:28 2017 -0400

    Add x86 and x86_64

 android/jni/Application.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

commit 3c51f005173a021d1bf6e8ecea22bc3b5fda08ba
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Mar 30 16:55:45 2017 -0400

    Fix the mono submodule.

 external/mono | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

commit e293d61090c9e8eb3a113a0d34be7ddd1e2c3597
Author: Bernhard Urban <bernhard.urban@xamarin.com>
Date:   Wed Mar 29 18:36:29 2017 -0400

    [readme] add links to specific NDK

 README.md | 6 ++++++
 1 file changed, 6 insertions(+)

commit 0985f1c448641484de6eac249f9cb9af1f1973b5
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Wed Mar 29 16:32:47 2017 -0400

    fix x86/x86_64 packaging.

 README.md        |  1 +
 sdks/Makefile    | 13 +++----------
 sdks/android.erb | 13 +++++++++++++
 3 files changed, 17 insertions(+), 10 deletions(-)

commit c0b9498d9afdaea48f474d31358a284b31d621e5
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Wed Mar 29 15:31:37 2017 -0400

    Add x86 and x86-84 to sdks.

 sdks/Makefile            | 15 +++++++++++++--
 sdks/android-template.rb | 33 +++++++++++++++++++++++++++++++++
 sdks/android.erb         |  4 ++--
 3 files changed, 48 insertions(+), 4 deletions(-)

commit 53778f4d473798123cf06896ffd2082517afc08d
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Wed Mar 29 11:40:18 2017 -0400

    small updates

 Makefile  | 7 ++++++-
 README.md | 5 +++++
 2 files changed, 11 insertions(+), 1 deletion(-)

commit 531603b66b630f3a46d1173124e202867f22460b
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Wed Mar 29 11:33:08 2017 -0400

    Add Android app.

 android/AndroidManifest.xml                        |  17 +
 android/Makefile                                   |  56 ++
 android/build.xml                                  |  92 ++++
 android/jni/Android.mk                             |  36 ++
 android/jni/Application.mk                         |   2 +
 android/jni/runtime-bootstrap.c                    | 588 +++++++++++++++++++++
 android/res/layout/main.xml                        |  22 +
 android/res/values/strings.xml                     |   4 +
 .../src/org/mono/android/main/AndroidRunner.java   | 136 +++++
 9 files changed, 953 insertions(+)

commit 2ae7f04e5fec696c83e47e8d938d9c9a3804beb8
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Wed Mar 29 11:05:30 2017 -0400

    Add C# test runner, build scripts and the needed machine.config.

 Makefile                            |  55 +------
 android/machine.config              | 278 ++++++++++++++++++++++++++++++++++++
 android/managed/Makefile            |  80 +++++++++++
 android/managed/fake-monodroid.cs   |  80 +++++++++++
 android/managed/main.cs             | 106 ++++++++++++++
 android/managed/mini-test-runner.cs |  74 ++++++++++
 6 files changed, 621 insertions(+), 52 deletions(-)

commit ded22bbf4a496e5e4a5fc9feb1f615698101718b
Author: Rodrigo Kumpera <kumpera@users.noreply.github.com>
Date:   Tue Mar 28 13:59:42 2017 -0400

    update readme

 README.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

commit f32b490b520da12a68f14ca6adfb00cb06b6733e
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Tue Mar 28 00:26:00 2017 -0400

    Initial set of scripts to build Android runtimes.

 .gitmodules              |  4 +++
 Makefile                 | 57 +++++++++++++++++++++++++++++++
 README.md                | 23 +++++++++++++
 external/mono            |  1 +
 paths.mk                 |  5 +++
 sdks/Makefile            | 83 +++++++++++++++++++++++++++++++++++++++++++++
 sdks/android-template.rb | 58 +++++++++++++++++++++++++++++++
 sdks/android.erb         | 88 ++++++++++++++++++++++++++++++++++++++++++++++++
 8 files changed, 319 insertions(+)

commit c61c02f2f30e513c3f2c471892158958e9a042ca
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Wed May 3 12:22:18 2017 -0700

    Build offsets & cross compilers, requires tip of kumpera/mono/naked-mono-goes-ios. Ready for cleanup-a-ton.

 sdks/ios.mk | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

commit 9b0f4522b96f7f9f91837859ad422e7a5c4300fb
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Tue May 2 19:56:22 2017 -0700

    add cross64.

 sdks/ios.mk | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

commit 1b03dc6552dd08b1690374e6b73d89a085b59a2e
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Tue May 2 19:55:30 2017 -0700

    add cross compilers. cross offset generation missing.

 sdks/ios.mk | 52 ++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 48 insertions(+), 4 deletions(-)

commit 1697337e706220185568eedf52b73e236521576a
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Tue May 2 17:38:52 2017 -0700

    add device64

 sdks/ios.mk | 115 ++++++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 92 insertions(+), 23 deletions(-)

commit 39f5ce7332d2d2cb7f9ca187f5d88f092f030d3c
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Tue May 2 13:18:15 2017 -0700

    missing files.

 ios/MonoTestRunner/main.cs | 106 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)

commit e3acb9682de0cf11ceda0ab38649c39fc7518b41
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Tue May 2 13:15:53 2017 -0700

    some IO stuff

 ios/MonoTestRunner/Makefile                        | 15 ++++--
 .../MonoTestRunner/Base.lproj/Main.storyboard      | 41 +++++++++++++++--
 ios/MonoTestRunner/MonoTestRunner/ViewController.m | 18 ++++++++
 .../MonoTestRunner/runtime-bootstrap.c             | 12 +++--
 .../MonoTestRunner/runtime-bootstrap.h             |  1 +
 .../MonoTestRunner/runtime-objc-helpers.m          | 53 +++++++++++++++++++++-
 6 files changed, 129 insertions(+), 11 deletions(-)

commit 5c83e9bb5bfdae13ff632d620b4d2a9896c83be3
Author: Rodrigo Kumpera <kumpera@gmail.com>
Date:   Thu Apr 20 15:41:43 2017 -0700

    Skeleton support for iOS. Sim only, not part of regular build.

 ios/MonoTestRunner/Makefile                        |  32 ++
 .../MonoTestRunner.xcodeproj/project.pbxproj       | 373 +++++++++++++++++++++
 ios/MonoTestRunner/MonoTestRunner/AppDelegate.h    |  17 +
 ios/MonoTestRunner/MonoTestRunner/AppDelegate.m    |  51 +++
 .../AppIcon.appiconset/Contents.json               |  93 +++++
 .../MonoTestRunner/Assets.xcassets/Contents.json   |   6 +
 .../Base.lproj/LaunchScreen.storyboard             |  27 ++
 .../MonoTestRunner/Base.lproj/Main.storyboard      |  26 ++
 ios/MonoTestRunner/MonoTestRunner/Info.plist       |  45 +++
 ios/MonoTestRunner/MonoTestRunner/ViewController.h |  15 +
 ios/MonoTestRunner/MonoTestRunner/ViewController.m |  32 ++
 ios/MonoTestRunner/MonoTestRunner/main.m           |  16 +
 .../MonoTestRunner/runtime-bootstrap.c             | 269 +++++++++++++++
 .../MonoTestRunner/runtime-bootstrap.h             |  16 +
 .../MonoTestRunner/runtime-objc-helpers.m          |  44 +++
 sdks/Makefile                                      |  10 +-
 sdks/ios.mk                                        | 177 ++++++++++
 17 files changed, 1245 insertions(+), 4 deletions(-)
 ```

1 files changed, 58 insertions, 0 deletions

diff --git a/sdks/builds/Makefile b/sdks/builds/Makefile
new file mode 100644
index 00000000000..d6cd2f90a8d
--- /dev/null
+++ b/sdks/builds/Makefile
@@ -0,0 +1,58 @@
+TOP=$(realpath $(CURDIR)/../..)
+include $(TOP)/sdks/paths.mk
+
+IS_RELEASE?=true
+
+$(TOP)/configure: $(TOP)/configure.ac $(TOP)/autogen.sh
+	cd $(TOP) && NOCONFIGURE=1 ./autogen.sh
+
+TARGETS=
+
+## BCL targets
+include bcl.mk
+
+## Android targets
+include android.mk
+
+## iOS targets
+include ios.mk
+
+## Generic targets
+.PHONY: $(foreach target,$(TARGETS),toolchain-$(target))
+$(foreach target,$(TARGETS),toolchain-$(target)): toolchain-%: .stamp-%-toolchain
+
+.PHONY: $(foreach target,$(TARGETS),configure-$(target))
+$(foreach target,$(TARGETS),configure-$(target)): configure-%: .stamp-%-configure
+
+.PHONY: $(foreach target,$(TARGETS),build-$(target))
+$(foreach target,$(TARGETS),build-$(target)): build-%: .stamp-%-configure
+	$(MAKE) -C $*
+
+.PHONY: $(foreach target,$(TARGETS),setup-$(target))
+$(foreach target,$(TARGETS),setup-$(target)): setup-%:
+	mkdir -p $(TOP)/sdks/out/$*
+
+.PHONY: $(foreach target,$(TARGETS),package-$(target))
+$(foreach target,$(TARGETS),package-$(target)): package-%: setup-% build-%
+
+.PHONY: $(foreach target,$(TARGETS),clean-$(target))
+$(foreach target,$(TARGETS),clean-$(target)):: clean-%:
+	rm -rf $(TOP)/sdks/out/$*
+
+## Global targets
+.PHONY: toolchain
+toolchain: $(foreach target,$(TARGETS),toolchain-$(target))
+
+.PHONY: configure
+configure: $(foreach target,$(TARGETS),configure-$(target))
+
+.PHONY: build
+build: $(foreach target,$(TARGETS),build-$(target))
+
+.PHONY: package
+package: $(foreach target,$(TARGETS),package-$(target))
+
+.PHONY: clean
+clean: $(foreach target,$(TARGETS),clean-$(target))
+
+all: package