port submission: qtchooser

[RJVB (René Bertin)]

Please find attached a portfile with an initial set-up for qtchooser, the utility that makes it possible/easy to have Qt4 and Qt5 (and soon enough probably Qt6) installed in parallel. It replaces certain of the standard Qt binaries (like qmake) with links to itself, and then uses configuration files and (optional) arguments to determine what version of the binary in question is called.

Thus, with qmake a symlink to qtchooser

> qmake --version              # prints the version of the default Qt installation
> qmake -qt=4 --version   # prints the version of the Qt4 installation
> qmake -qt=5 --version   # prints the version of the Qt5 installation

What's missing are the configuration files that will determine which Qt goes and is expected where, though I have given an upbeat by assuming that'd be ${prefix}/libexec/qtN .

I hope this helps and brings the possibility to have concurrent qt4-mac and qt5-mac installs a step closer.