virt-manager: Exit on ctrl-c

pygobject3 doesn't provide this automatically. Solution taken from:

https://bugzilla.gnome.org/show_bug.cgi?id=622084

virt-manager

@@ -272,6 +272,15 @@ def main():
     LibvirtGLib.init(None)
     LibvirtGLib.event_register()
 
+    # Actually exit when we receive ctrl-c
+    from gi.repository import GLib
+    def _sigint_handler(user_data):
+        ignore = user_data
+        logging.debug("Received KeyboardInterrupt. Exiting application.")
+        sys.exit(0)
+    GLib.unix_signal_add(GLib.PRIORITY_DEFAULT, signal.SIGINT,
+                         _sigint_handler, None)
+
     engine = vmmEngine()
 
     engine.start(options.uri, show_window, domain, options.skip_autostart)