server-main: Add quit()

This allows to exit the mainloop e.g. when signalled from gnome-session
or by a signal.

src/server-main.c

@@ -50,9 +50,16 @@ struct squeekboard {
 };
 
 
+GMainLoop *loop;
 static gboolean opt_system = FALSE;
 static gchar *opt_address = NULL;
 
+static void
+quit (void)
+{
+  g_main_loop_quit (loop);
+}
+
 // D-Bus
 
 static void
@@ -307,8 +314,7 @@ main (int argc, char **argv)
 
     session_register();
 
-    GMainLoop *loop = g_main_loop_new (NULL, FALSE);
-
+    loop = g_main_loop_new (NULL, FALSE);
     g_main_loop_run (loop);
 
     if (connection) {