Make sure gcc4.6 is not used

Cherry pick https://gerrit.chromium.org/gerrit/#/c/71645/

Intrinsic support in gcc4.6 is poor. Make sure it is not being used.

Since the vp8_shortwalsh4x4 function has not previously caused any
build failures, this patch should not have any effect in Chromium.

TBR=tomfinegan@chromium.org

Review URL: https://codereview.chromium.org/597033002

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/libvpx@292105 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
2 files changed