[TEST] netgraph callout interface

  Dear collegues,

  we are working on making netgraph ISR mpsafe. To do it we need to
fix all (ab)users of bare timeout(9) in src/sys/netgraph. These
timeout calls are running in synch with netgraph now because timeout(9)
is Giant-locked. As soon as we mark ISR mpsafe, they are going to break.

This patch semi-mechanically changes all timeout(9) calls to ng_callout(9),
which runs scheduled callouts in netgraph context:

	http://people.freebsd.org/~glebius/totest/netgraph_callout

It can be applied to HEAD or RELENG_5 (not 5.3-RELEASE). It patches
the following nodes:

	ng_bridge.c
	ng_l2tp.c
	ng_lmi.c
	ng_ppp.c
	ng_pppoe.c
	ng_tty.c

If you are using at least one of them, then I'm asking you to test the
patch and respond. Thanks in advance!

P.S. Sorry for crossposting. The target users are both RELENG_5 and CURRENT.

-- 
Totus tuus, Glebius.
GLEBIUS-RIPN GLEB-RIPE