MFC r260070

 MFC r260070

 Multi-queue NIC drivers and multi-port lagg tend to use the same lower
 bits of the flowid as each other, resulting in a poor distribution of
 packets among queues in certain cases.  Work around this by adding a
 set of sysctls for controlling a bit-shift on the flowid when doing
 multi-port aggrigation in lagg and lacp.  By default, lagg/lacp will
 now use bits 16 and higher instead of 0 and higher.

Obtained from:	Netflix

git-svn-id: svn://svn.freebsd.org/base/stable/10@260179 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f