GitLab

Fixes: debbugs:19404

* gnutls.c (init_gnutls_functions): Import gnutls_x509_crt_check_issuer.
(Fgnutls_peer_status): Use it to set the :self-signed flag.
Rename the previous :self-signed to :unknown-ca.
(Fgnutls_peer_status_warning_describe): Explain :unknown-ca flag.