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.

src/video/wayland/SDL_waylandmessagebox.c

@@ -223,7 +223,7 @@ int Wayland_ShowMessageBox(const SDL_MessageBoxData *messageboxdata, int *button
         output = SDL_malloc(output_len + 1);
         if (!output) {
             close(fd_pipe[0]);
-            return SDL_OutOfMemory();
+            return -1;
         }
         output[0] = '\0';