Use -fstack-protector in Mac Debug builds.
Use -fstack-protector in Mac Debug builds.

We used to have this in debug.xcconfig, but it seems to have gotten lost when
we migrated to GYP.

BUG=16713 (not really, that's for release builds, but close enough)
TEST=none
Review URL: http://codereview.chromium.org/292036

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@29591 0039d316-1c4b-4281-b951-d872f2087c98

gavinp/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,ropik/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,Crystalnix/house-of-life-chromium