Fix invalid handling of verify errors in libssl

Fix invalid handling of verify errors in libssl

In the event that X509_verify() returned an internal error result then
libssl would mishandle this and set rwstate to SSL_RETRY_VERIFY. This
subsequently causes SSL_get_error() to return SSL_ERROR_WANT_RETRY_VERIFY.
That return code is supposed to only ever be returned if an application
is using an app verify callback to complete replace the use of
X509_verify(). Applications may not be written to expect that return code
and could therefore crash (or misbehave in some other way) as a result.

CVE-2021-4044

Reviewed-by: Tomas Mraz <tomas@openssl.org>