V8 has had a trace event macro interface for while, but without a tracing
controller a standalone V8 would be unable to collect traces.

This CL introduces a complete Tracing Controller system for V8.
It is fully function except that it does not yet store trace event args.

This CL has a few components,
The tracing controller itself, contributed by the author of this CL
The Trace config (including the parser), contributed by lpy@
The Trace Object, Trace Writer, and Trace Buffer are all contributed by rksang@

BUG=v8:4561
LOG=N

Review-Url: https://codereview.chromium.org/2137013006
Cr-Commit-Position: refs/heads/master@{#38073}