This was the only thing that made SDL_config.h generate differently between
32 and 64-bit versions of Linux, so instead we force a function cast in our
X11 code to match our dynamic loader version, which removes the compile error
on some machines that prompted this test in the first place.
Xlib never wrote to this data, so if you're on an older Xlib where this param
wasn't const, your data should still be intact when we force the caller to
think it was actually const after all.
Fixes Bugzilla #1893.
An existing hint lets apps that don't need the timer resolution changed avoid
this, to save battery, etc, but this fixes several problems in timing, audio
callbacks not firing fast enough, etc.
Fixes Bugzilla #2944.
