MFC r255944:

  Use MK_SSP=no after including bsd.own.mk to disable SSP instead of user-knob
  WITH[OUT]_SSP to avoid hitting an error if user has WITH_SSP in their
  make.conf. Ports now use this knob.

    make[7]: "/usr/src/share/mk/bsd.own.mk" line 466: WITH_SSP and
    WITHOUT_SSP can't both be set.

Approved by:	bapt
Merge r253680,253805 from head:
  ----------------------------------------------------------------------
  r253680 | des | 2013-07-26 19:53:43 +0400 (Fri, 26 Jul 2013) | 7 lines

  Implement certificate verification, and many other SSL-related
  imrovements; complete details in the PR.

  PR:             kern/175514
  Submitted by:   Michael Gmelin <freebsd@grem.de>
  MFC after:      1 week

  ----------------------------------------------------------------------
  r253805 | des | 2013-07-30 17:07:55 +0400 (Tue, 30 Jul 2013) | 5 lines

  Include an Accept header in requests.

  PR:             kern/180917
  MFC after:      1 week

Reviewed by:	des