Check full SHA digests in unit tests
The current test_crypto_sha unit test only checks the first 20 bytes of each digest. (The buffer sizes are somewhat out of whack, as we discovered in #17699 (moved).)
While it won't change the outcome of the tests, we really should check the entire length of each hash.
See my branch sha-unit-tests on https://github.com/teor2345/tor.git