Integrate with google/oss-fuzz

[nathaniel-brough]

Hey I'd like to suggest adding sha256-simd to google/oss-fuzz. If you aren't familiar with fuzz testing, here is a bit of a run down (from Wikipedia);

In programming and software development, fuzzing or fuzz testing is an automated software testing technique that involves providing invalid, unexpected, or random data as inputs to a computer program. The program is then monitored for exceptions such as crashes, failing built-in code assertions, or potential memory leaks.

Google offers a free continuous fuzzing service called OSS-fuzz. If sha256-simd is integrated into oss-fuzz, the fuzz tests under sha256-simd will be built and then run once a day, to search for bugs and vulnerabilities in sha256-simd. This service can be integrated with the CI for sha256-simd, so that the fuzz tests are run for 10min or so for every pull request, preventing buggy code from being merged.

I've opened up a pull request to add a basic fuzz-testing harness here #69. If you are keen on adding sha256-simd to oss-fuzz I'd be happy to champion the integration :)

[klauspost]

I don't think this package has a long life ahead of itself, now that golang/go#50543 is merged into Go.

So YES to adding the fuzz test. NO to adding it to ossfuzz.