[compiler-rt] Include assembly files in builtins library build

[sgundapa]

Summary

This patch address the PR20360. The CMake assembler build system
ignores the .S assembly files in builtins library build. This patch
fixes the issue.

[sgundapa]

I don't have commit access.
Can some one merge this ?

[rengolin]

r213684

[rengolin]

Reverted in r213724 since it broke the sanitizer bot:

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/4016

cheers,
--renato

[sgundapa]

I will check on what the issue is

lib/builtins/CMakeLists.txt

set(arm_SOURCES
   arm/unordsf2vfp.S
   ${GENERIC_SOURCES})
 
 add_custom_target(builtins)
 
 if (NOT WIN32)
   foreach(arch x86_64 i386 arm)
     if(CAN_TARGET_${arch})
+      set_source_files_properties(${${arch}_SOURCES} PROPERTIES LANGUAGE C)
       add_compiler_rt_runtime(clang_rt.builtins-${arch} ${arch} STATIC
         SOURCES ${${arch}_SOURCES}
         CFLAGS "-std=c99")
       add_dependencies(builtins clang_rt.builtins-${arch})
     endif()
   endforeach()
 endif()
 
 add_dependencies(compiler-rt builtins)