ok: add basic unit test support

Plenty TODO remaining.

This can actually kind of run without a test reporter or GrContext:
    $ out/ok test
    784 ok, 56 crashed
    ... lots of stack traces ...
Most tests don't use the reporter unless they're going to fail.

Change-Id: I7333e2c63ade5e671ebf60022d19390f1fc1c93a
Reviewed-on: https://skia-review.googlesource.com/10201
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>
3 files changed