Merge the [pgoyette-compat] branch

Prepare for new compat_netbsd32_mqueue module to be split out of
compat_netbsd32. Refactor the COMPAT_50 code related to mqueue,
and update the syscall definitions. Remove dependency on mqueue
from

Prepare for new compat_netbsd32_mqueue module to be split out of
compat_netbsd32. Refactor the COMPAT_50 code related to mqueue,
and update the syscall definitions. Remove dependency on mqueue
from the compat_netbsd32 module (the new module will gain this
dependency).

Continuation of work on PR kern/50489

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whitespace police.

Fix reversed arguments in copyin(9), c.f. kern/sys_mqueue.c rev 1.39.

Move compat calls, requested by mrg@

Fix compat/versioning confusion and add the missing new versioned ones.

Implement modctl, sigqueinfo and mq_*