Client/Inode: wait_for_caps fixups

Client/Inode: wait_for_caps fixups

The non-blocking flush requires us to be able to re-add to
wait_for_caps but if we simply add to the list, we get stuck in an
infinite loop. Add a wait_for_caps_pending list to add to, and then
when done signalling, we move the wait_for_caps_pending items onto the
wait_for_caps list.

Also in handle_cap_flush_ack(), we need to complete the caps flushing
before signalling since with non-blocking flush, we will be actually
examining the caps from the completion rather than signalling a
condition variable in the completion.

Signed-off-by: Frank S. Filz <ffilzlnx@mindspring.com>