Centralizes all the nasty behaviour that will end up breaking when WINE
eventually turns on userspace syscall dispatch. Pushes all of the logic
in to the UnixLib. Support both paths until everyone is migrated to
supporting the UnixLib, then we can delete the bit of code duplication
between the PE side and UnixLib side.
Helpful that everything that gets punched through the UnixLib is
optional, so worst case some optional bits can break for a while.
Allows WTF to work (mostly) with Wine by letting us VirtualName things,
and also allows madvise control of THP, which significantly cuts back
memory usage.
This works around the problem of Wine not giving us control of this by
using raw syscalls when wine is detected.
Based on top of #5362 so the THP disable controls are in.
Ryan Houdek