[skshaper] Build tweaks

Preps for building in Chromium & G3.

Change-Id: I4eb802f27aac7d3652c3b3ce427dcc758d6c31fe
Reviewed-on: https://skia-review.googlesource.com/c/185000
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
4 files changed