gpsbabel suddenly based on qt5-mac thus leaving qt4-mac-based port qlandkartegt in limbo

[Marko Käning]

I just realised that updated gpsbabel [1] leaves qlandkartegt in limbo because of
switching to qt5-mac:
---
$ port deps gpsbabel
Full Name: gpsbabel @1.5.2_0
Build Dependencies:   pkgconfig
Library Dependencies: qt5-mac, expat, libusb-compat, zlib
$ port rdependents gpsbabel
The following ports are dependent on gpsbabel:
  qlandkartegt
---

How to transition from Qt4 to Qt5 more smoothly?? This is going to happen for many
ports in the future, so, perhaps this is a port where one could try to exercise how
to do it least disturbingly for users having installed qt4-mac ports?!

I - for my part - am still having a fully qt4-mac-based MacPorts system for production,
which is why I don’t want such automagic transitions to Qt5, unless all dependent ports
have also migrated to Qt5.

	Any ideas?

Greets,
Marko




[1] https://trac.macports.org/ticket/47721