[skottie] Add skottie_tool srcs/includes to public.bzl

Change-Id: I5f45a967031ff8d02ea24483807944be64ec5270
Reviewed-on: https://skia-review.googlesource.com/c/169823
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
1 file changed