Use SDL_InitFlags for the SDL_Init* function implementations

src/SDL.c

@@ -215,7 +215,7 @@ static void SDL_QuitMainThread(void)
     SDL_main_thread_initialized = SDL_FALSE;
 }
 
-int SDL_InitSubSystem(Uint32 flags)
+int SDL_InitSubSystem(SDL_InitFlags flags)
 {
     Uint32 flags_initialized = 0;
 
@@ -431,12 +431,12 @@ quit_and_error:
     return -1;
 }
 
-int SDL_Init(Uint32 flags)
+int SDL_Init(SDL_InitFlags flags)
 {
     return SDL_InitSubSystem(flags);
 }
 
-void SDL_QuitSubSystem(Uint32 flags)
+void SDL_QuitSubSystem(SDL_InitFlags flags)
 {
     /* Shut down requested initialized subsystems */
 
@@ -527,7 +527,7 @@ void SDL_QuitSubSystem(Uint32 flags)
     }
 }
 
-Uint32 SDL_WasInit(Uint32 flags)
+Uint32 SDL_WasInit(SDL_InitFlags flags)
 {
     int i;
     int num_subsystems = SDL_arraysize(SDL_SubsystemRefCount);