This is based on the existing gnome-keyring helper, but instead of
libgnome-keyring (which was specific to GNOME and is deprecated), it
uses libsecret which can support other implementations of XDG Secret
Service API.
Passes t0303-credential-external.sh.
Signed-off-by: Mantas Mikulėnas <grawity@gmail.com>
Reviewed-by: Dennis Kaarsemaker <dennis@kaarsemaker.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>