wine{alsa,pulse}: Merge unixlib.h, move it into mmdevapi

Merged Davide Beatrici requested to merge davidebeatrici/wine:mmdevapi-unixlib.h into master

This is the very first step for merging the mmdevdrv.c files into a single one.

The commit strictly focuses on Linux drivers, wine{oss,coreaudio} will follow.

Huge thanks to @jacek and @huw for making this simple, as they took care of ELF/PE separation.

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