tcp_lro: When processing compressed acks lets support the new early wake feature for rack.

[rrs]

Summary

During compressed ack and mbuf queuing we determine if we need to wake up. A
new function was added that is optional to the tfb so that the stack itself can also
be asked if a wakeup should happen. This helps compensate for late hpts calls.

Test Plan

Use dtrace to make sure that with an LRO interface we are calling in
to the rack supported function (when using the rack stack of course). Also
make sure (via bb logs) that if it returns true LRO actually wakes the connection.