error: SDL's allocators now call SDL_OutOfMemory on error.

This means the allocator's caller doesn't need to use SDL_OutOfMemory directly
if the allocation fails.

This applies to the usual allocators: SDL_malloc, SDL_calloc, SDL_realloc
(all of these regardless of if the app supplied a custom allocator or we're
using system malloc() or an internal copy of dlmalloc under the hood),
SDL_aligned_alloc, SDL_small_alloc, SDL_strdup, SDL_asprintf, SDL_wcsdup...
probably others. If it returns something you can pass to SDL_free, it should
work.

The caller might still need to use SDL_OutOfMemory if something that wasn't
SDL allocated the memory: operator new in C++ code, Objective-C's alloc
message, win32 GlobalAlloc, etc.

Fixes #8642.

test/testshape.c

@@ -144,7 +144,7 @@ static int SDL3_SetWindowShape(SDL_Window *window, SDL_Surface *shape, SDL_Windo
     g_bitmap_h = shape->h;
     g_bitmap = (Uint8*) SDL_malloc(shape->w * shape->h);
     if (!g_bitmap) {
-        return SDL_OutOfMemory();
+        return -1;
     }
 
     SDL_CalculateShapeBitmap(*shape_mode, shape, g_bitmap, 1);