Move skPaint2GrPaint to SkGr.h/cpp

BUG=skia:
R=bsalomon@google.com, brian@thesalomons.net, robertphillips@google.com

Author: egdaniel@google.com

Review URL: https://codereview.chromium.org/283803003

git-svn-id: http://skia.googlecode.com/svn/trunk@14753 2bbb7eff-a529-9590-31e7-b0007b416f81
3 files changed