Qt doesn't compile with QT_NO_DEBUG_OUTPUT and QT_NO_WARNING_OUTPUT defined

The documentation suggests to set those defines to make qDebug and qWarning not do anything:

http://doc.trolltech.com/4.3/qtglobal.html#qDebug
http://doc.trolltech.com/4.3/qtglobal.html#qWarning
http://doc.trolltech.com/4.3/debug.html

However, adding those defines to release.prf to make a release build of Qt not print any errors does not compile.