Switch tun(4) from encapsualting packets into a long mbuf chain over to use mbuf clusters if the packet is big enough. This should speed up tun(4) and may help in other cases where long mbuf chains hurt. Additionally switch the default tun(4) MTU to a more sane 1500 bytes. TUNMTU is kept because it is used in userland. Input and OK from brad@ and djm@
Switch tun(4) from encapsualting packets into a long mbuf chain over to use
mbuf clusters if the packet is big enough. This should speed up tun(4) and
may help in other cases where long mbuf chains hurt.
Additionally switch the default tun(4) MTU to a more sane 1500 bytes.
TUNMTU is kept because it is used in userland.
Input and OK from brad@ and djm@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars