Fix SpritePacker build on Mac OS X platform.

Source/Tools/SpritePacker/CMakeLists.txt

@@ -29,4 +29,7 @@ define_source_files ()
 include_directories(../../ThirdParty/STB)
 
 # Setup target
+if (APPLE)
+    setup_macosx_linker_flags (CMAKE_EXE_LINKER_FLAGS)
+endif ()
 setup_executable ()