message: Fix makefile benchmark script to build on mac os.
  Mac linker does not have -Wl,--whole-archive.
diff: @@ -339,11 +339,18 @@ $(BENCHMARK_LIB) : $(LIB_PATH) $(BENCHMARK_LIB_OBJS)
  benchmark_lib: $(BENCHMARK_LIB)
  +BENCHMARK_LINKOPTS :=
  +ifeq ($(HOST_OS),osx)
  + BENCHMARK_LINKOPTS += $(LIBFLAGS) -Wl,-force_load $(BENCHMARK_LIB) $(LIBS) $(LDFLAGS) -framework CoreFoundation
  +else
  + BENCHMARK_LINKOPTS += $(LIBFLAGS) -Wl,--whole-archive $(BENCHMARK_LIB) -Wl,--no-whole-archive $(LDFLAGS) $(LIBS)
  +endif
  +
  $(BENCHMARK_BINARY) : $(BENCHMARK_MAIN_OBJ) $(BENCHMARK_LIB)
  @mkdir -p $(dir $@)
  $(CXX) $(CXXFLAGS) $(INCLUDES) \
  -o $(BENCHMARK_BINARY) $(BENCHMARK_MAIN_OBJ) \
  - $(LIBFLAGS) -Wl,--whole-archive $(BENCHMARK_LIB) -Wl,--no-whole-archive $(LDFLAGS) $(LIBS)
  + $(LIBFLAGS) $(BENCHMARK_LINKOPTS)
  $(BENCHMARK_PERF_OPTIONS_BINARY) : $(BENCHMARK_PERF_OPTIONS_OBJ) $(BENCHMARK_LIB)
  @mkdir -p $(dir $@)
  