VFS: Fix up posix_same_owner() so that it only uses the
   file_lock->fl_owner field when determining lock equality.

VFS: Fix up posix locking routines to use posix_same_owner() instead
   of rolling their own checks.
Signed-off-by: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>