remove unused SkMeshUtils and SkBoundaryPatch

BUG=skia:6366

Change-Id: Ibacd397e0a246dbeefde074c98712ada3848a7b6
Reviewed-on: https://skia-review.googlesource.com/9852
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
5 files changed