MFC r283101:

MFC r283101:
  Teach key_expire() send SADB_EXPIRE message with the SADB_EXT_LIFETIME_HARD
  extension header type. The key_flush_sad() now will send SADB_EXPIRE
  message when HARD lifetime expires. This is required by RFC 2367 and some
  keying daemons rely on these messages. HARD lifetime messages have
  precedence over SOFT lifetime messages, so now they will be checked first.
  Also now SADB_EXPIRE messages will be send even the SA has not been used,
  because keying daemons might want to rekey such SA.

  PR:		200282, 200283

MFC r283102:
  Change SA's state before sending SADB_EXPIRE message. This state will
  be reported to keying daemon.