Note that this removes the timeGetTime() fallback on Windows; it is a
32-bit counter and SDL2 should never choose to use it, as it only is needed
if QueryPerformanceCounter() isn't available, and QPC is _always_ available
on Windows XP and later.
OS/2 has a similar situation, but since it isn't clear to me that similar
promises can be made about DosTmrQueryTime() even in modern times, I decided
to leave the fallback in, with some heroic measures added to try to provide a
true 64-bit tick counter despite the 49-day wraparound. That approach can
migrate to Windows too, if we discover some truly broken install that doesn't
have QPC and still depends on timeGetTime().
Fixes#4870.
Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.
More extensive documentation is available in the docs directory, starting
with README.md