gpg-agent: Avoid getting stuck in shutdown pending state.

* agent/gpg-agent.c (handle_connections): Always check inotify fds.

I noticed a gpg-agent processed, probably in shutdown_pending state,
which was selecting on only these two inotify fds. The select
returned immediately but because we did not handle the fds in
shutdown_pending state they were not read and the next select call
returned one of them immediately again. Actually that should not
hanppen because the

if (active_connections == 0)
  break; /* ready */

should have terminated the loop. For unknown reasons (maybe be just a
connection thread terminated in a gdb session) that did not happen.
By moving the check outside of the shutdown_pending condition and
closing the fd after they have been triggered the code should be more
robust.

• Signed-off-by: Werner Koch <wk@gnupg.org>