This CL adds fuzzing support, in the form of GN logic, docs, and an
example fuzzer.
You can run this fuzzer with the following:
$ pw_fuzzer/examples/build_and_run_toy_fuzzer.sh
This is rather bare-bones at the moment. Additional features, like
corpus and dictionary integration, more sanitizers, etc. are follow-on
work.
Change-Id: I7fb4d5ecbb59d1e9b69f4594db4222728b8da2f9