Remove in-line NULL-checks before SDL_free()

[eloj]

This may have already been discussed and rejected before, in which case I apologize for the noise, but I got inspired by a recent change merged to mesa.

This branch contains the result of applying a coccinelle spatch to remove basic NULL checks before SDL_free():

@@
expression ptr;
@@

-if (ptr) {
-SDL_free(ptr);
-}
+SDL_free(ptr);

@@
expression ptr;
@@

-if (ptr != NULL) {
-SDL_free(ptr);
-}
+SDL_free(ptr);

I also 'manually' did the same for free(), but there were only three occurences.

[slouken]

Hmm, we probably don't want the coccinelle patch, but otherwise, @icculus, how do you feel about this?

[slouken]

Actually, POSIX explicitly states that free(NULL) does nothing, so I think I'm okay with this.

[icculus]

This is fine. I clean these out when I find them, so it's nice to have it all done at once.

We don't need the coccinelle patch.

[eloj]

Rebased and ready to go. (The RISCOS build failed to bring up the container.)

[1bsyl]

maybe we can keep the patch, so that it can be run once in a while

[slouken]

Merged, thanks!

[eloj]

That was my original intent by including it @1bsyl, that maybe you'd want to make it e.g part of the checklist for releasing a major version. I didn't actually hook/link it into anything because I didn't want to add work for maintainers out of the blue.

The spatch is trivial, but I pasted it into the top post for posterity.