This doesn't create any apps or bundles or sign anything, but it all compiles and links.
Note the awkward transitional hack I used to make each tool's tool_main() serve as the real main() again when built with GN, while keeping the existing setup with GYP. Fun...
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4350
Change-Id: I632753d5d8e5848380854f413bf5905d676bfcf4
Reviewed-on: https://skia-review.googlesource.com/4350
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
