SDL_properties.c: mark CleanupFreeableProperty and CleanupSurface as SDLCALL

src/SDL_properties.c

@@ -375,7 +375,7 @@ int SDL_SetProperty(SDL_PropertiesID props, const char *name, void *value)
     return SDL_PrivateSetProperty(props, name, property);
 }
 
-static void CleanupFreeableProperty(void *userdata, void *value)
+static void SDLCALL CleanupFreeableProperty(void *userdata, void *value)
 {
     SDL_free(value);
 }
@@ -385,7 +385,7 @@ int SDL_SetFreeableProperty(SDL_PropertiesID props, const char *name, void *valu
     return SDL_SetPropertyWithCleanup(props, name, value, CleanupFreeableProperty, NULL);
 }
 
-static void CleanupSurface(void *userdata, void *value)
+static void SDLCALL CleanupSurface(void *userdata, void *value)
 {
     SDL_Surface *surface = (SDL_Surface *)value;