let setup-qt detect qmake-qt4 and qmake-qt5 executables
let setup-qt detect qmake-qt4 and qmake-qt5 executables

Some Linux distributions provide qmake binaries that are called
qmake-qt4 and qmake-qt5. Let setup-qt find those in auto-detection mode.

Change-Id: Iaf3ac087ab05201a4d2823629236b46167e6e1c1
Task-number: QBS-745
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@theqtcompany.com>

qt-labs/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,gatzka/qt-labs-qbs,qt-labs/qbs