[MacPorts] #71479: qt5 5.15.x does not build on Mojave and earlier; different default needed there

[MacPorts]

#71479: qt5 5.15.x does not build on Mojave and earlier; different default needed
there
--------------------------+-------------------------------------
 Reporter:  barracuda156  |      Owner:  MarcusCalhoun-Lopez
     Type:  defect        |     Status:  assigned
 Priority:  Normal        |  Milestone:
Component:  ports         |    Version:  2.10.5
 Keywords:                |       Port:  qt5-qttools, qt5-qtbase
--------------------------+-------------------------------------
 For example: https://ports.macports.org/port/qt5-qttools/details

 Perhaps if 5.15.x does not build, rather set some sensible default for
 older systems?

 Otherwise dependents are broken.

-- 
Ticket URL: <https://trac.macports.org/ticket/71479>
MacPorts <https://www.macports.org/>
Ports system for macOS