Append ROCm flag to compile definitions for Python instead of overwri…

…ting (facebookresearch#3742)

Summary:
Pull Request resolved: facebookresearch#3742

Before this change, the CMake line was setting (instead of appending to) compile definitions for Python code which replace the GPU wrappers flag and resulting in Python library compiling with no GPU code which failed ROCm tests.

Reviewed By: junjieqi

Differential Revision: D61007640

fbshipit-source-id: 174aeb0a4abe0607629ddf57c882d19ea2d6c6bf

faiss/python/CMakeLists.txt

@@ -39,7 +39,7 @@ macro(configure_swigfaiss source)
       COMPILE_DEFINITIONS GPU_WRAPPER
     )
     if (FAISS_ENABLE_ROCM)
-      set_source_files_properties(${source} PROPERTIES
+      set_property(SOURCE ${source} APPEND PROPERTY
         COMPILE_DEFINITIONS FAISS_ENABLE_ROCM
       )
     endif()