so the annoying message is not printed.
o Don't warn about FUTEX_FD not being implemented
and return ENOSYS instead of 0 (eg. success).
o Clear FUTEX_PRIVATE_FLAG as we actually implement
only private futexes so there is no reason to
return ENOSYS when app asks for a private futex.
We don't reject shared futexes because they worked
just fine with our implementation so far.
Approved by: kib (mentor)
Tested by: bsam
MFC after: 1 week
6af821237d