test: test hmac binding robustness

The Hmac binding layer is not documented as part of the API, and is not
intended to be used, but it should be robust to misuse, and contains
defensive checks for misuse. This test checks that updates without init
throw (as opposed to abort or misbehave in some other way).

PR-URL: https://github.com/nodejs/node/pull/10923


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>