The return values of OCSP_check_nonce() can be checked to cover each case. A
positive return value effectively indicates success: nonces are both present
-and match, both absent or present in the response only. A non-zero return
+and match, both absent or present in the response only. A nonzero return
additionally covers the case where the nonce is present in the request only:
this will happen if the responder doesn't support nonces. A zero return value
indicates present and mismatched nonces: this should be treated as an error