remove most of SDL_OutOfMemory() calls where SDL is the allocator.

Since commit 447b508a77, SDL_malloc,
SDL_calloc, and SDL_realloc already calls SDL_OutOfMemory().

src/storage/steam/SDL_steamstorage.c

@@ -151,7 +151,6 @@ static SDL_Storage *STEAM_User_Create(const char *org, const char *app, SDL_Prop
 
     steam = (STEAM_RemoteStorage*) SDL_malloc(sizeof(STEAM_RemoteStorage));
     if (steam == NULL) {
-        SDL_OutOfMemory();
         return NULL;
     }