Bug is: "IRIX: X BadMatch when trying to start any 640x480 game".
40e019efd4 introduced resetting the pixel depth
when unloading modes for SDL output. This was required to make mode listing
for OpenGL work on Win8+.
This causes issues on non-Win32 platforms though. SDL might not give us a valid
a pixel depth, causing the resetting to fail. A particular example is X11 on
IRIX, when only 16bit output modes work. Initially SDL tells us that the pixel
depth is 32bit. Trying to set this up causes a crash though.
Since there is no way to validate SDL's return value, we simply limit the reset
to platforms where it is actually required, i.e. Win32.
fd688b73d7