I did some further searching, without success. What I found, however:
  • Unlike /usr/bin/qmake-qt4 the debug version was not executable (it is now; but did not help)
  • When I add in QtCreator to the setting 'Qt Versions' /usr/lib/debug/usr/bin/qmake-qt4 as additonal version, the dialog states that /usr/lib/debug/usr/bin/qmake-qt4 is no valid Qt installation (in German: 'keine gültige Qt-Installation').
  • The debug qmake-qt4 seems to erroneously use the Qt version in /usr/lib, i.e., the non-debug version:
    /usr/lib/debug/usr/bin$ qmake-qt4 -v
    QMake version 2.01a
    Using Qt version 4.6.2 in /usr/lib


What am I doing wrong?