MFC r215338:

MFC r215338:
  - print out the PID and program name of the program trying to use an
    unsupported futex operation
  - for those futex operations which are known to be not supported,
    print out which futex operation it is
  - shortcut the error return of the unsupported FUTEX_CLOCK_REALTIME in
    some cases:
      FUTEX_CLOCK_REALTIME can be used to tell linux to use
      CLOCK_REALTIME instead of CLOCK_MONOTONIC. FUTEX_CLOCK_REALTIME
      however must only be set, if either FUTEX_WAIT_BITSET or
      FUTEX_WAIT_REQUEUE_PI are set too. If that's not the case
      we can die with ENOSYS right at the beginning.

  Submitted by:	arundel
  Reviewed by:	rdivacky (earlier iteration of the patch)
  MFC after:	1 week

git-svn-id: svn://svn.freebsd.org/base/stable/8@215661 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f