Add 'public' headers support to find_headers.py

Update the script to search for headers in both 'sources' and 'public'.

Change-Id: I195c6e3720f3d3d99dea04628388821a58fa791b
Reviewed-on: https://skia-review.googlesource.com/130823
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed