There are a few loose ends following the conversion of md to use kthreads:

- Some fields in mdk_thread_t that aren't needed (kthreads does it's own
  completion and manages it's own name).

- thread->run is now never NULL, so no need to check

- Some tests for signal_pending that aren't needed (As we don't use signals
  to stop threads any more)

- Some flush_signals are not needed

- Some waits are interruptible and don't need to be.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>