Test ocsp with invalid responses and the "-no_cert_checks" option

The "-no_cert_checks" option causes the flag OCSP_NOCHECKS to be set.
The bug fixed in the previous commit will cause the ocsp app to respond with
a success result in the case when the OCSP response signing certificate
fails to verify and -no_cert_checks is used - so we test that it fails in
this case.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
