utils: add macros to suppress compiler warnings

Signed-off-by: Thomas Haller <thaller@redhat.com>
gconf-helpers: suppress deprecated warning for gnome-keyring-1

libgnome-keyring is marked as deprecated in favour of libsecret.
We only use it for the legacy gconf-helpers. That code will be
removed in the future, so don't bother an just suppress the
deprecation warning.

Signed-off-by: Thomas Haller <thaller@redhat.com>