add fatstroke sample

BUG=skia:

Change-Id: I7d5d2c76cba8ac566e2900697b913ea18e7695dd
Reviewed-on: https://skia-review.googlesource.com/6120
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed