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

3 files changed, 1 insertions, 6 deletions

diff --git a/sbin/route/keywords b/sbin/route/keywords
index 8b64be28d384..82edc46690d1 100644
--- a/sbin/route/keywords
+++ b/sbin/route/keywords
@@ -40,7 +40,6 @@ osi
 prefixlen
 proto1
 proto2
-proto3
 proxy
 recvpipe
 reject
diff --git a/sbin/route/route.8 b/sbin/route/route.8
index 000fbe9c1874..5e6f78b4e017 100644
--- a/sbin/route/route.8
+++ b/sbin/route/route.8
@@ -28,7 +28,7 @@
 .\"     @(#)route.8	8.3 (Berkeley) 3/19/94
 .\" $FreeBSD$
 .\"
-.Dd January 11, 2014
+.Dd November 11, 2014
 .Dt ROUTE 8
 .Os
 .Sh NAME
@@ -315,7 +315,6 @@ by indicating the following corresponding modifiers:
 -blackhole RTF_BLACKHOLE  - silently discard pkts (during updates)
 -proto1    RTF_PROTO1     - set protocol specific routing flag #1
 -proto2    RTF_PROTO2     - set protocol specific routing flag #2
--proto3    RTF_PROTO3     - set protocol specific routing flag #3
 .Ed
 .Pp
 The optional modifiers
diff --git a/sbin/route/route.c b/sbin/route/route.c
index 604057d147d7..2c328a39c41d 100644
--- a/sbin/route/route.c
+++ b/sbin/route/route.c
@@ -847,9 +847,6 @@ newroute(int argc, char **argv)
 			case K_PROTO2:
 				flags |= RTF_PROTO2;
 				break;
-			case K_PROTO3:
-				flags |= RTF_PROTO3;
-				break;
 			case K_PROXY:
 				nrflags |= F_PROXY;
 				break;