Consolidated, consistent rt target fixes single-threaded build

1 files changed, 7 insertions, 2 deletions

diff --git a/util/Jamfile b/util/Jamfile
index c292e0da3..d4996e483 100644
--- a/util/Jamfile
+++ b/util/Jamfile
@@ -11,8 +11,13 @@ if [ test_library "lzma" ] && [ test_header "lzma.h" ] {
   compressed_deps += lzma ;
 }
 
-#rt is needed for clock_gettime on linux.  But it's already included with threading=multi
-lib rt ;
+local have-clock = [ SHELL "bash -c \"g++ -dM -x c++ -E /dev/null -include time.h 2>/dev/null |grep CLOCK_MONOTONIC\"" : exit-status ] ;
+if $(have-clock[2]) = 0 {
+  #required for clock_gettime.  Threads already have rt.  
+  lib rt : : <runtime-link>static:<link>static <runtime-link>shared:<link>shared ;
+} else {
+  alias rt ;
+}
 
 obj read_compressed.o : read_compressed.cc : $(compressed_flags) ;
 alias read_compressed : read_compressed.o $(compressed_deps) ;