When adding a default route, make the route static. Since this is a ``manually

When adding a default route, make the route static. Since this is a ``manually
added route'', this arguably follows the network programming guidelines.
This is necessary, otherwise it is impossible to make the default route
stick in the presense of routed(8). There is a small fix that needs to
be applied to routed(8) in if.c (iflookup) where we always want to look
for interfaces *once* instead of waiting for the timeout period. This avoids
the race where routed finds the route added by pppd before it finds that the
ppp inteface is now active. With those two fixes, pppd can happily coexist
with routed.