Clean up modules/skottie/BUILD.gn

Per comments in https://skia-review.googlesource.com/c/skia/+/130480

Change-Id: I978b04e4b06bf01c008b44540c640b77f5900f12
Reviewed-on: https://skia-review.googlesource.com/130501
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
1 file changed