SDL use static libraries (#409)

mac/CMakeLists.txt

@@ -83,7 +83,7 @@ set_target_properties(GLESv2 PROPERTIES
 
 add_library(SDL2 SHARED IMPORTED GLOBAL)
 set_target_properties(SDL2 PROPERTIES
-  IMPORTED_LOCATION ${CMAKE_CURRENT_LIST_DIR}/libs/libSDL2-2.0.0.dylib
+  IMPORTED_LOCATION ${CMAKE_CURRENT_LIST_DIR}/libs/libSDL2.a
 )
 
 set(se_libs_name)
@@ -211,6 +211,9 @@ list(APPEND CC_EXTERNAL_LIBS
     webp
     curl
     SDL2
+    # sdl2 depends on the following two libraries.
+    "-framework IOKit"
+    "-framework Carbon"
     ${glslang_libs_name}
     ${spirv-cross_libs_name}
     ${tbb_libs_name}