bridge(4) input path fixing

[Matthew Dillon]

:If some unexpected recursion happened, your box may panic.  This
:probably would not happen.  I don't think dead lock problem would be
:introduced by this patch.
:
:Best Regards,
:sephe
:
:-- 
:Live Free or Die

    I was able to do some minimal testing with if_tap and vkernel bridging.
    I think it may be best to commit it now, so we can get some wider testing
    in while we are still a month away from the 1.10 release.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>