Fix build with QT_NO_DEBUG_OUTPUT defined

The use of the qDebug() macro to construct a QDebug object fails when
QT_NO_DEBUG_OUTPUT is defined when building Qt.
This patch aims to fix this.

[ChangeLog][General][Build] Can now build with QT_NO_DEBUG_OUTPUT
defined

Change-Id: If807ee3439db2a98b4d146f75860a98f40c247ec
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>