In r227207, to fix the issue with possible NULL inp_socket pointer
dereferencing, when checking for SO_REUSEPORT option (and SO_REUSEADDR
for multicast), INP_REUSEPORT flag was introduced to cache the socket
option.  It was decided then that one flag would be enough to cache
both SO_REUSEPORT and SO_REUSEADDR: when processing SO_REUSEADDR
setsockopt(2), it was checked if it was called for a multicast address
and INP_REUSEPORT was set accordingly.

Unfortunately that approach does not work when setsockopt(2) is called
before binding to a multicast address: the multicast check fails and
INP_REUSEPORT is not set.

Fix this by adding INP_REUSEADDR flag to unconditionally cache
SO_REUSEADDR.

PR:		179901
Submitted by:	Michael Gmelin freebsd grem.de (initial version)
Reviewed by:	rwatson
MFC after:	1 week
The T5 allows the driver to specify the ISS.  Do so; use the ISS picked
by the kernel.

MFC after:	1 day
Whitespace fixes: remove tabs on blank links, spaces following content,
tabs after spaces.

Reviewed by:	gjb
MFC after:	1 week
The tvp vnode on rename is usually unlinked.  Drop the cached null
vnode for tvp to allow the free of the lower vnode, if needed.

PR:	kern/180236
Tested by:	smh
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Ring the egress queue's doorbell as soon as there are 8 or more
descriptors ready to be processed.

MFC after:	1 day