Fix compile error in XCB when XInput version < 2.2

Add version guards to prevent compiler error:
'XITouchClass' was not declared in this scope
in systems having XInput version < 2.2.

Change-Id: Ib1308f29ef97288eb994ab8bdd668199ca2ee1d7
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

src/plugins/platforms/xcb/qxcbconnection_xi2.cpp

@@ -175,9 +175,11 @@ void QXcbConnection::xi2SetupDevices()
             case XIKeyClass:
                 qCDebug(lcQpaXInputDevices) << "   it's a keyboard";
                 break;
+#ifdef XCB_USE_XINPUT22
             case XITouchClass:
                 // will be handled in deviceForId()
                 break;
+#endif
             default:
                 qCDebug(lcQpaXInputDevices) << "   has class" << devices[i].classes[c]->type;
                 break;