Update the base64 regress test and enable a test that would previously

Update the base64 regress test and enable a test that would previously
have resulted in a segfault. Also update the resulting output bytes now
that the invalid/corrupt input is detected and rejected; unless you're
using BIO_FLAGS_BASE64_NO_NL, in which case you still get a stream of
zero value bytes and no way of knowing that the data is invalid/corrupt.