IFLIB updates:
We found routing performance dropped significantly when configuring
FreeBSD as a router, we are applying the following changes in order to
resolve those issues and hopefully perform better.

• don't prefetch the flags array, we usually don't need it
• prefetch the next cache line of each of the software descriptor arrays as well as the first cache line of each of the next four packets' mbufs and clusters
• reduce max copy size to 63 bytes
• convert rx soft descriptors from array of structures to a structure of arrays
• update copyrights

Submitted by: Matt Macy <mmacy@nextbsd.org>