Revert "Handle new QtTraceMsg type, fix warnings about unhandled enumeration value."

This reverts commit bf49d9f0d41c3be802dbdd2c23dfe7c5fd86f4b0.
QtTraceMsg was removed from QtCore for the moment, too.

Change-Id: I1d6aaacf5e363f81272da4fbb0a4ff12337dd677
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>