Use ip{,6}_send() instead of ip{,6}_output() to prevent a recursion.

Use ip{,6}_send() instead of ip{,6}_output() to prevent a recursion.

if_start() is a boundary between the network stack and drivers.  The
states it modifies must be protected by the driver, so we should not
require the NET_LOCK() there.

ok bluhm@, visa@