These files don't #include SDL headers, so SDL-specific macros will
never be defined here.
This partially reverts commit 31d133db.
Fixes: 31d133db "Define SDL_PLATFORM_* macros instead of underscored ones (#8875)"
Signed-off-by: Simon McVittie <smcv@collabora.com>
Much of the heavy lifting of this optimization is lifted from the Pixman
project, which is distributed under an MIT-style license. As far as possible,
these elements have been relicensed to the zlib license.