[MacPorts] #60080: qt513-qtwebengine fails building (on MacOS 10.12)

[MacPorts]

#60080: qt513-qtwebengine fails building (on MacOS 10.12)
---------------------+--------------------
 Reporter:  Greisby  |      Owner:  (none)
     Type:  defect   |     Status:  new
 Priority:  Normal   |  Milestone:
Component:  ports    |    Version:
 Keywords:           |       Port:
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 The compilation fails with lots of errors "unrecognized platform name
 macOS"

 Example:
 {{{
 :info:build ./../../3rdparty/chromium/base/process/launch_mac.cc:97:27:
 error: unrecognized platform name macOS
 :info:build   if (__builtin_available(macOS 10.12, *)) {
 }}}

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Ticket URL: <https://trac.macports.org/ticket/60080>
MacPorts <https://www.macports.org/>
Ports system for macOS