Add G_DBUS_SIGNAL_FLAGS_NO_MATCH_RULE

If specified, the signal subscription is setup client-side but the match
rule is not sent to the server.  This allows the caller to manually
register more detailed match rules.

gio/gioenums.h

@@ -1157,6 +1157,9 @@ typedef enum
 /**
  * GDBusSignalFlags:
  * @G_DBUS_SIGNAL_FLAGS_NONE: No flags set.
+ * @G_DBUS_SIGNAL_FLAGS_NO_MATCH_RULE: Don't actually send the AddMatch
+ * DBus call for this signal subscription.  This gives you more control
+ * over which match rules you add (but you must add them manually).
  *
  * Flags used when subscribing to signals via g_dbus_connection_signal_subscribe().
  *
@@ -1164,7 +1167,8 @@ typedef enum
  */
 typedef enum /*< flags >*/
 {
-  G_DBUS_SIGNAL_FLAGS_NONE = 0
+  G_DBUS_SIGNAL_FLAGS_NONE = 0,
+  G_DBUS_SIGNAL_FLAGS_NO_MATCH_RULE = (1<<0)
 } GDBusSignalFlags;
 
 /**