fix test-api-fill c++ compilation

Author: daanx

CMakeLists.txt

@@ -175,7 +175,7 @@ endif()
 if(MI_USE_CXX)
   message(STATUS "Use the C++ compiler to compile (MI_USE_CXX=ON)")
   set_source_files_properties(${mi_sources} PROPERTIES LANGUAGE CXX )
-  set_source_files_properties(src/static.c test/test-api.c test/test-stress PROPERTIES LANGUAGE CXX )
+  set_source_files_properties(src/static.c test/test-api.c test/test-api-fill test/test-stress PROPERTIES LANGUAGE CXX )
   if(CMAKE_CXX_COMPILER_ID MATCHES "AppleClang|Clang")
     list(APPEND mi_cflags -Wno-deprecated)
   endif()