Fix SkottieKit font loading

The current build configuration (empty fontmgr) doesn't support loading
custom fonts.

For full/npm builds, use the custom fontmgr.

Change-Id: Ifd623fdbac2d5723a04add6fc455188fb3dc96e1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/305816
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Auto-Submit: Florin Malita <fmalita@chromium.org>
2 files changed