MFC r286074:

MFC	r286074:
GCC: Add a new option "-fstack-protector-strong"

This includes additional functions to be protected: those that
have local array definitions, or have references to local frame
addresses. This is a new option in GCC-4.9 that was relicensed
by Han Shen from Google under GPLv2.

Obtained from:	OpenBSD (2014-01-14)

git-svn-id: svn://svn.freebsd.org/base/stable/9@286714 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f