This small patch fixes gre tunnels using keys (and probably 
sequencing/checksums) in 2.{5,6}.
If params aren't set before ipgre_tunnel_init is called, it 
miscalculates the header size, and
stomps on itself when encapsulating packets.

I'm not sure if the later initialization can be removed, or if this is 
the *correct* patch. It does
allow tunnels to work here.

-pee

(this might be a double send, i sent it last sunday, but didn't see it 
show up in the lists)