Description: when Qt4 is installed alongside Qt5, qmake should be Qt4.

Additional info:
While working in a Qt4 based application with Thiago Macieira, from the Qt Project, the following conversation was made:

<thiago> anyway, I want to make that an error.
<tomaz> if you make that an error, how would I compile on my sistem that has qt5 and qt4?
<thiago> qmake is qt4
<tomaz> qmake is qt5 here.
<thiago> that's wrong
<thiago> qmake must be qt4 if qt4 is installed
<tomaz> â subsurface git:(master) â qmake --version
<tomaz> QMake version 3.0
<tomaz> Using Qt version 5.0.2 in /usr/lib
<thiago> is that qtchooser?
<thiago> or is that the real qmake?
<tomaz> real qmake.
<thiago> well, your distro is non-standard
<thiago> it's wrong, unsupported and *specifically* banned by the Qt Project
<thiago> report a bug
<thiago> they MUST change. qmake must default to Qt 4.
<tomaz> â subsurface git:(master) â which qmake
<tomaz> /usr/bin/qmake
<thiago> qmake -list-versions
<thiago> what distro is that?
<tomaz> â subsurface git:(master) â qmake -list-versions
<tomaz> ***Unknown option -list-versions
<tomaz> Arch
<thiago> please report a bug
<thiago> they are wrong, they must fix it
<tomaz> ok.
<tomaz> but while they doesn't, how should I compile when you set that to fail?
<thiago> qmake must be qt 4
<thiago> so fix the distro
<thiago> to find Qt 5, you set QT_SELECT=5 and qmake will know where it is

Steps to reproduce:
always