flag parameters: NONBLOCK in anon_inode_getfd

Building on the previous change to anon_inode_getfd, this patch introduces
support for handling of O_NONBLOCK in addition to the already supported
O_CLOEXEC.  Following patches will take advantage of this support.  As can be
seen, the additional support for supporting this functionality is minimal.

Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>