deps_builder : copy llvm headers to lib folder.

Were not needed previously, but the functions branch needs them.

build_files/build_environment/cmake/harvest.cmake

@@ -129,6 +129,8 @@ harvest(jpg/include jpeg/include "*.h")
 harvest(jpg/lib jpeg/lib "libjpeg.a")
 harvest(lame/lib ffmpeg/lib "*.a")
 harvest(clang/bin llvm/bin "clang-format")
+harvest(clang/include llvm/include "*.h")
+harvest(llvm/include llvm/include "*.h")
 harvest(llvm/bin llvm/bin "llvm-config")
 harvest(llvm/lib llvm/lib "libLLVM*.a")
 if(APPLE)