dix: warn about keyboard events with valuator masks

We don't actually handle the mask correctly. They're clipped and dropped
into the event but that's about it. I don't think we did since 1.4, let's
warn the user if this happens.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>

dix/getevents.c

@@ -919,6 +919,11 @@ GetKeyboardEvents(InternalEvent *events, DeviceIntPtr pDev, int type,
        (key_code < 8 || key_code > 255))
         return 0;
 
+    if (mask_in && valuator_mask_size(mask_in) > 1) {
+        ErrorF("[dix] the server does not handle valuator masks with "
+                "keyboard events. This is a bug. You may fix it.\n");
+    }
+
     num_events = 1;
 
     events = UpdateFromMaster(events, pDev, DEVCHANGE_KEYBOARD_EVENT, &num_events);