Add compile flag to force usage of distance fields for all SkPaints.

BUG=skia:2173
R=reed@google.com, robertphillips@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/195213003

git-svn-id: http://skia.googlecode.com/svn/trunk@13770 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed