part of the hal distribution early on when the hal was built for
each os but it's been portable for a long time so move the os-specific
code out (and off the vendor branch)
o correct the copyright on ah_osdep.?; it was mistakenly given a
restricted license and not a dual-bsd/gpl license
o remove the module api definition as it was never used
o fixup include paths for move of ah_osdep.h
MFC after: 2 weeks
3fe92528af