Merge r256824 from head:

Merge r256824 from head:
  Provide a working example line for an interface with 1 address running
  with CARP.

  Currently, we've got a problem that interface isn't IFF_UP at the time
  we assign it a redundant address, and the latter gets stuck in INIT state.
  Additional SIOCSIFFLAGS from ifconfig(8) kicks it to a working state.

  A proper fix is kernel side and appeared to be non-trivial, not to be
  checked in before 10.0-RELEASE.

  Submitted by:   Ole Myhre <ole.myhre dataoppdrag.no>

Approved by:	re (kib)

git-svn-id: svn://svn.freebsd.org/base/stable/10@257321 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f