Don't send an reply for driver messages if one isn't requested

Basically honor the no_reply flag; a binding is likely to want to
set this so it doesn't have to process extra traffic for match
rules.

bus/driver.c

@@ -32,6 +32,7 @@
 #include "utils.h"
 #include <dbus/dbus-string.h>
 #include <dbus/dbus-internals.h>
+#include <dbus/dbus-message.h>
 #include <dbus/dbus-marshal-recursive.h>
 #include <string.h>
 
@@ -791,6 +792,9 @@ send_ack_reply (DBusConnection *connection,
 {
   DBusMessage *reply;
 
+  if (dbus_message_get_no_reply (message))
+    return TRUE;
+
   reply = dbus_message_new_method_return (message);
   if (reply == NULL)
     {