[MacPorts] #60511: move to quartz as default backend

[MacPorts]

#60511: move to quartz as default backend
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  Reporter:  ra1nb0w                             |      Owner:  mascguy
      Type:  enhancement                         |     Status:  assigned
  Priority:  Normal                              |  Milestone:
 Component:  ports                               |    Version:
Resolution:                                      |   Keywords:
      Port:  R Togl VLC VLC2 avahi cairo         |
  cairomm cherrytree clutter cogl gWakeOnLAN     |
  gconf gegl geoclue2 glade glib2 glibmm gnome-  |
  themes-extra gnubg gnucash-docs gtk-sharp2     |
  gtk2 gtk3 gtkextra3 gtkimageview gtkmm gtkmm3  |
  gtkspell2 inkscape lablgtk2 libVLC libVLC2     |
  librsvg meld netgen opencolorio pan2 pango     |
  pangomm pdfpc pidgin pspp py-cairo py-gobject  |
  py-pygtk reinteract tix tk tkdnd tkimg         |
  tktable ufraw webkit2-gtk wxgtk-3.0            |
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Comment (by holymonson):

 FYI, this repo https://gitlab.gnome.org/GNOME/gtk-osx, owned by the gnome
 team, holds version-locks and patches to build MacOS application bundles
 for Gtk+-based applications. And they builds with +quartz (and higher
 webkit2-gtk). We may follow their steps cause they have better experience
 building gtk apps on macos.

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Ticket URL: <https://trac.macports.org/ticket/60511#comment:57>
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