We should rely on OpenSSL to do this for us instead. Doing it here is wrong because we wind up checking certificates that may not actually be used in the final certificate chain constructed by OpenSSL. We don't have any way to know which chain OpenSSL will build from the certificates that we pass to it, so there is no way to safely perform certificate validity checks at the glib-networking level.
Fixes #179 (closed)
Corresponding change for GTlsDatabaseGnutls: a2cc9b8e
Corresponding change for GTlsCertificateGnutls: e1a8d066
Documented by: glib@780af9cf