Remove kernel handling of ICMP_SOURCEQUENCH.
It hasn't been used for a very long time.
Additionally, it was deprecated by RFC 6633.
- fix typo: use ring size from the rx ring, not the tx one (they should be
  the same, but just in case);
- reuse the previously computed len-1 value
in the Linux section, properly define the NMG_LOCK type.
Also import WITH_GENERIC in preparation to adding fine-grained
options to disable specific netmap components.
Kill custom in_matroute() radix mathing function removing one rte mutex lock.

Initially in_matrote() in_clsroute() in their current state was introduced by
r4105 20 years ago. Instead of deleting inactive routes immediately, we kept them
in route table, setting RTPRF_OURS flag and some expire time. After that, either
GC came or RTPRF_OURS got removed on first-packet. It was a good solution
in that days (and probably another decade after that) to keep TCP metrics.
However, after moving metrics to TCP hostcache in r122922, most of in_rmx
functionality became unused. It might had been used for flushing icmp-originated
routes before rte mutexes/refcounting, but I'm not sure about that.

So it looks like this is nearly impossible to make GC do its work nowadays:

in_rtkill() ignores non-RTPRF_OURS routes.
route can only become RTPRF_OURS after dropping last reference via rtfree()
which calls in_clsroute(), which, it turn, ignores UP and non-RTF_DYNAMIC routes.

Dynamic routes can still be installed via received redirect, but they
have default lifetime (no specific rt_expire) and no one has another trie walker
to call RTFREE() on them.

So, the changelist:
* remove custom rnh_match / rnh_close matching function.
* remove all GC functions
* partially revert r256695 (proto3 is no more used inside kernel,
  it is not possible to use rt_expire from user point of view, proto3 support
  is not complete)
* Finish r241884 (similar to this commit) and remove remaining IPv6 parts

MFC after:	1 month
Add baud rate support to telnet(1)

This implements part of RFC-2217

It's based off a patch originally written by Sujal Patel at Isilon, and
contributions from other Isilon employees.

PR: 173728
Phabric: D995
Reviewed by: markj, markm
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division
Revert WiP to contrib/tzcode accidentally committed with r274364
Add missing privilege check when setting the dump device. Before that change it
was possible for a regular user to setup the dump device if he had write access
to the given device. In theory it is a security issue as user might get access
to kernel's memory after provoking kernel crash, but in practise it is not
recommended to give regular users direct access to storage devices.

Rework the code so that we do privileges check within the set_dumper() function
to avoid similar problems in the future.

Discussed with:	secteam
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Rename variable name from 'index' to 'idx' to avoid shadowing index(3).

Noticed by:	dim
MFC after:	2 weeks
Move struct ether_vlan_header to ethernet.h, out of if_vlan_var.h,
since this structure is protocol definition, not part of implementation.
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Fix some minor TSO issues:
- Improve description of TSO limits.
- Remove a not needed KASSERT()
- Remove some not needed variable casts.

Sponsored by:	Mellanox Technologies
Discussed with:	lstewart @
MFC after:	1 week
On 965 and higher, map GTT as write-combining.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Based on some BIOS configuration (GGC register in host bridge, bit 1),
IGP may declare subclass as either VGA-compatible, or non-VGA.  The
difference is that in the later case, IGP does not claim VGA cycles.
Other than that, the device functions normally, and agp_i810 should
attach to it.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Initial attachment of the agp(4) to Haswell IGP.  There is no handling
of cacheablility control bits in GTT PTEs yet.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Fix gcc build: preserve const qualifier when casting input values.

Noticed by:	bz@
Submitted by:	dim@
Update comment.

Noted by:	dim
Approved by:	secteam (des)
MFC after:	4 days
Add workaround for vt efifb's early use of PHYS_TO_DMAP

In vt_efifb_init the framebuffer's physaddr is passed to PHYS_TO_DMAP
before the DMAP is setup. The result is not actually accessed until
after the mapping is setup, though. Loosen the assertion in PHYS_TO_DMAP
for now, to allow use when dmaplimit == 0.

Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D1142
Test errno against EEXIST as well.

MFC after:	3 days
Remove myself from bxe(4) maintenance.