It seems to have been deprecated. This gets --host builds working,
although some libs don't work properly due to having only dlls and I
guess mingw stuff isn'n on any paths.
Only 64-bit windows is tested, and there are still various failures, but
QF is limping along in windows again.
nq-sdl works for sw, and sw32, gl and glsl are mostly black (but not
entirely for gl?), vulkan is not supported with sdl.
nq-win works for sw and sw32, and sort of for vulkan (very dark and
upside-down?). gl and glsl complain about vid mode,
qw-client-[sdl,win] seem to be the same, but something is wrong with the
console (reading keyboard input).
Most of the guts of configure.ac have been moved to config.d and are then
brought in by m4_include. This will make maintaining configure.ac much easier.
Also drop use of PROGRAM and VERSION, using PACKAGE_NAME, PACKAGE_VERSION, and
on occasion, PACKAGE_STRING instead, and clean out some old files we no longer
need.
