MFC r275392:

MFC r275392:
  Remove route chaching support from ipsec code. It isn't used for some time.
  * remove sa_route_union declaration and route_cache member from struct secashead;
  * remove key_sa_routechange() call from ICMP and ICMPv6 code;
  * simplify ip_ipsec_mtu();
  * remove #include <net/route.h>;

Sponsored by:	Yandex LLC

git-svn-id: svn://svn.freebsd.org/base/stable/10@283901 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f