Add gn_to_bp.py.

The general idea here is, run GN in --ide=json mode to get most information.

Then, read a couple .gni files to get the rest (platform specific source lists, Android framework defines).

For now, I'm generating Android.bp and SkUserConfig.h.  I figure we can do DM and nanobench once these work?

Change-Id: I8e7f60d6572f2d4769760cf872895518a15d841b
Reviewed-on: https://skia-review.googlesource.com/5554
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
2 files changed