Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add more fields to if_debug.c for ddb(4) 'show ifnet'; resort
some fields to match the order in the struct. Especially needed
if_pf_kif to do pf(4) VNET debugging.

Approved by: re (marius)
Obtained from: projects/vnet
MFC after: 1 week
Sponsored by: The FreeBSD Foundation

Add more fields from struct ifnet needed during debugging a kernel panic.
Move if_fib into the right place.

MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

Catch up with some more fields. I needed the bpf one lately.

Sponsored by: The FreeBSD Foundation

Remove ifq_drops from struct ifqueue. Now queue drops are accounted in
struct ifnet if_oqdrops.

Some netgraph modules used ifqueue w/o ifnet. Accounting of queue drops
is simply removed from them. There were no API to read this statistic.

Sponsored by: Netflix
Sponsored by: Nginx, Inc.

Add infrastructure to allow all frames/packets received on an interface
to be assigned to a non-default FIB instance.

You may need to recompile world or ports due to the change of struct ifnet.

Submitted by: cjsp
Submitted by: Alexander V. Chernikov (melifaro ipfw.ru)
(original versions)
Reviewed by: julian
Reviewed by: Alexander V. Chernikov (melifaro ipfw.ru)
MFC after: 2 weeks
X-MFC: use spare in struct ifnet

Factor out DDB commands from r204145, r204279 into if_debug.c for further
enhancements (1). Switch to a standard 2-clause BSD license for this (2).

Unfortunately we have to un-static the ifindex_table for this but do not
publicly export it.

Suggested by: rwatson (1) a while back.
Approved by: thompsa (2) for the change from r204279.
MFC after: 6 days