OpenSSLX509Certificate: use OID if alg name unavailable

If we cannot map the signature OID type to a canonical name, then we
should try to get an instance of the signature type using the OID.
Additionally, we should return the OID for the #getSigAlgName instead of

Bug: 22365511
Change-Id: I1ebf48667cf720ee5c7751667601eec2f6f8ec91
1 file changed