Issue 22830:  Clarify docs for functools.cmp_to_key().
merge
Issue 20152, 22821: Port the fcntl module to Argument Clinic.

Along the way, fix an argumrnt to fcntl.fcntl to be an int instead of
a long.

Thanks to Serhiy Storchaka for reviewing my Clinic patch and for
writing the patch to fix the long/int issue.
Merge with default