Add SDL_abort macro

[madebr]

Using the non-libc SDL_abort instead of abort on Linux gives the same developer experience:
The debugger immediately jump to the SDL_abort location.
This is why SDL_abort is a macro instead of an inline/extern function.

The only observable difference is the signal triggering the debugger, and what's printed on the terminal on abort.

abort from libc:

Aborted (core dumped)

abort using SDL_TriggerBreakpoint + SDL_ExitProcess:

Illegal instruction (core dumped)

Description

Existing Issue(s)

Fixes #13968

[slouken]

We probably want to declare SDL_ExitProcess outside the block scope. If I remember right, some compilers don't like that. Do we need the __WATCOMC__ stuff here?

[madebr]

I was hesitant about doing that because of this comment. Or perhaps this comment is talking about the public headers.

/* This is not declared in any header, although it is shared between some
    parts of SDL, because we don't want anything calling it without an
    extremely good reason. */

[madebr]

Can Watcom compile SDL3 for Windows/Linux? @sezero

[madebr]

But if I can declare SDL_ExitProcess in SDL_internal.h, then I can just keep the watcom code.

[sezero]

(Sorry for late reply - noticed this one late.)

Can Watcom compile SDL3 for Windows/Linux? @sezero

Never tested building sdl3 itself using watcom, and never will: unsupported. So, watcom stuff can be removed from private sdl3 sources.

P.S.: Headers are still compatible, though: sdl2-compat can still build for windows using watcom.

[sezero]

So, watcom stuff can be removed from private sdl3 sources.

... and just did that with 9cefbab