Replace old hack with SDL_HasSurfaceRLE

[Starbuck5]

In surface.c we have the function pg_HasSurfaceRLE, which accesses SDL internals my mimicking one of their structs, to get access to whether the surface has RLE or not.

SDL 2.0.14 had a new function SDL_HasSurfaceRLE that seems to do the same thing, but with less code on our end. This will be necessary for SDL3 support, as the internal structures are even more hidden in SDL3.

Wrinkle is that we still support down to SDL 2.0.10.

Possible path: use the old code if below 2.0.14, use the new code if at or above 2.0.14 (including SDL3)

[Starbuck5]

Wow, igordsm actually set this up already in the form of PG_SurfaceHasRLE in #2491