[MacPorts] #62982: qt6: add port(s) for new Qt version 6

[MacPorts]

#62982: qt6: add port(s) for new Qt version 6
--------------------------+--------------------
  Reporter:  JDLH         |      Owner:  (none)
      Type:  request      |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:  2.7.1
Resolution:               |   Keywords:
      Port:  qt6 qt5 qt4  |
--------------------------+--------------------

Comment (by jhoyt4):

 @reneeotten I had no issues compiling qt6-base with two machines (one
 intel, one arm/M1) both were running Big Sur.

 I went the ninja route because of notes on qt's site heavily suggesting
 using ninja.  Cmake is certainly an option, but I had some issues
 correctly translating (and locating...) all of the configure flags and
 found using the configure script to be easier to troubleshoot.

 In regards to the subports - cmake is also a viable option, I started
 there but then read some qt release notes heavily suggesting usinf qt-
 configure_module.

 I just looked at your fork and all of the changes look very reasonable
 (wish I caught several myself :) )

-- 
Ticket URL: <https://trac.macports.org/ticket/62982#comment:8>
MacPorts <https://www.macports.org/>
Ports system for macOS