GitLab

Fixed the few remaining warnings and turned on warning as error on Linux.

Explicitly turned off warning as error in libjpeg, cityhash and json.
Review URL: https://codereview.chromium.org/12521010

git-svn-id: http://skia.googlecode.com/svn/trunk@8067 2bbb7eff-a529-9590-31e7-b0007b416f81