This gets rid of the bloated memmap_win32.c in favour of a much simpler
wrapper. This will be needed in the future since the wrapper does not
support MAP_FIXED maps (necessary for some platforms)
Let's see, this should fix issues on platforms that do not support
running the emu at 59.73 FPS. We run the emu at fake 60fps, which means
we produce more audio samples than the original device.
Instead of missing samples (which produce cracks in the audio) we should
be producing some extra samples, which will result in a frame drop every
now and then (like every minute or so, so it's not noticeable).