Highlights:
*Building with msys2 can now take advantage of sdl-config and sdl2-config if present.
*Add a header check to error out if SDL_mixer's major version does not match SDL.
*Building with frameworks on OS X works again.
Notes:
*Those cross compiling, particularly targeting Windows, may need to invoke make with SDLCONFIG='' to avoid bringing in libs and headers from the host.
git-svn-id: https://svn.eduke32.com/eduke32@5778 1a8010ca-5511-0410-912e-c29ae57300e0
This needs improvements to bring it up to par with winlayer, but it is functional. In particular, a good amount of code from winlayer could be used for both layers, including the profiling timers, the version printing code, and the hInstance and hModule sharing.
Known problems: the mouse cursor is not trapped, and the game starts before the startup window shows options.
git-svn-id: https://svn.eduke32.com/eduke32@3219 1a8010ca-5511-0410-912e-c29ae57300e0
