-Fast bot upgrades

  - GCC -> Clang;
  - Add a Perf bot.

This -Fast mode is a stand-in for "how clients should/do really release code".  Today everyone uses Clang, so we should probably switch this bot too.

I also got interested in how it compares in performance to our ordinary Release build, so I've added a Perf bot.

I did try turning on link-time optimization (much slower build, somewhat faster binary), but that failed at the link step.  Going to save that for later.


Change-Id: I58e6109f8a89799d80e769316902549131b619cf
Reviewed-on: https://skia-review.googlesource.com/6595
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
tree: cabb4bdbf5b5f8579efeace7c4b4f2bf4d15ae49
  1. recipe_modules/
  2. recipes.py
  3. recipes/