test/xi2: fail if xi2 class type is garbage. (#25492)

If the keycode range exceeds the allowable length, memory gets overwritten.
Catch this case by making sure that only allowed class types are
present.

X.Org Bug 25492 <http://bugs.freedesktop.org/show_bug.cgi?id=25492>

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

test/xi2/protocol-eventconvert.c

@@ -736,6 +736,9 @@ static void test_values_XIDeviceChangedEvent(DeviceChangedEvent *in,
 
                 }
                 break;
+            default:
+                g_error("Invalid class type.\n");
+                break;
         }
 
         ptr += any->length * 4;