koops: fix a use-after-free bug uncoverd by coverity

Signed-off-by: Jakub Filak <jfilak@redhat.com>
applet: disable GDK deprecation warnings

GtkStatusIcon is going to be dropped from gtk-3, but we cannot stop
using it because we have to support other desktop environments than
GNOME Desktop.

Related to #836

Signed-off-by: Jakub Filak <jfilak@redhat.com>