Allow downloading of source packages of Blender's dependencies, so that
it's easier to provide a "full source archive" that contains the blender
source + all dependencies archives. A `make` command for this will be
introduced soon.
This changes the deps builder slightly to be more flexible with the
origin of our source packages.
To support this a new CMake variable has been added called `PACKAGE_DIR`
where all sources archives will be stored.
default: a directory called `packages` in the build folder.
alternative-default: if a directory called `packages` exists in the
blender source folder that will be used. This is to support the "full
source archive" use case.
The download phase have been moved from the build phase to the configure
phase. Configure will download all sources validate the hashes while
downloading.
All `[depname].cmake` files have been changed to take a local
`file://[path_to_local_tarball]` path rather than a remote URI.
A second requirement was that there needed to be an option to grab the
sources from the blender SVN mirror rather than upstream. For this an
option has been added PACKAGE_USE_UPSTREAM_SOURCES (default ON). The
exact location in SVN still needs to be worked out, I tested with my
local webserver and codewise it checks out. The path that is in there
currently will not work (given there is no mirror there yet).
To build this mirror our local package caches can be used.
Reviewed By: lazydodo
Differential Revision: https://developer.blender.org/D10598
