Add kAAHairline to GpuPathRenderers

With the upcoming ccpr stroking, this will no longer be the only path
renderer that can handle hairlines.

Bug: skia:
Change-Id: Idf2543f053c8603c80fcd647ca18ffd9860a85f3
Reviewed-on: https://skia-review.googlesource.com/142246
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
4 files changed