Initial version of the correctness fuzzer harness for manual testing
and experiments.

For automated usage, some outstanding TODOs are left in the code. E.g.
- Hash source file names in error case
- Bundle script in out directory with executables
- Some suppressions are tied to already fixed bugs. We'll keep it like that for now to test
removing those suppressions in production later.

BUG=chromium:673246
NOTRY=true

Review-Url: https://codereview.chromium.org/2578503003
Cr-Commit-Position: refs/heads/master@{#41789}