only skip pf once for packets that are injected by a divert-packet socket.

only skip pf once for packets that are injected by a divert-packet socket.

when a divert socket gets a packet from userland to send back through
the kernel, it marks it as diverted so pf knows not to divert it
back to userland again. this marking stuck to the packet though,
so if it went through pf again (eg, on the way out of the network
stack) pf would skip it again. this is undesirable if you want pf
to do things to the packet on this outgoing hope, such as nat.

this has pf clear the mark once it's been used, which allows the
next run of a packet through pf to have stuff work on it.

found by some people at parta networks.
ok sashan@ lteo@ bluhm@
bluhm@ also suggested keeping my diff in the same style as the rest of pf.c