Disable LTCG for Qt WebEngineCore

We do not have it working together with the building of Chromium.

Task-number: QTBUG-66571
Change-Id: Ib000a4102b02902f2ac257347e406297fe1608cf
Reviewed-by: Samuli Piippo <[email protected]>

Author: Allan Sandfeld Jensen

src/core/core_common.pri

@@ -6,3 +6,6 @@ QT += qml quick webchannel
 QT_PRIVATE += quick-private gui-private core-private webenginecoreheaders-private
 
 qtHaveModule(positioning):QT += positioning
+
+# LTO does not work for Chromium at the moment, so disable it completely for core.
+CONFIG -= ltcg