Add option to specify defaults configs to --config flag in gm. This makes it easier to run gm defaults configs with a delta. Also make ~ exclude a config.

Review URL: https://codereview.chromium.org/13842014

git-svn-id: http://skia.googlecode.com/svn/trunk@8842 2bbb7eff-a529-9590-31e7-b0007b416f81
14 files changed