[MacPorts] #70824: legacy-support provide TARGET_OS_IPHONE

[MacPorts]

#70824: legacy-support provide TARGET_OS_IPHONE
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 Reporter:  rmottola  |      Owner:  (none)
     Type:  defect    |     Status:  new
 Priority:  Normal    |  Milestone:
Component:  ports     |    Version:
 Keywords:            |       Port:  legacy-support
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 I noticed that several ports start "breaking" because of TARGET_OS_IPHONE
 not being defined.
 E.g. https://github.com/LuaJIT/LuaJIT/pull/1189/files

 The fix is incredibly trivial, but upstream often forgets about that. We
 can fight and make a patch for each and maintain it or hope it is
 upstreamed.
 However, often legacy-support is already used. I wonder if there is a good
 place and way to define it? Of course to 0, NO, or what is needed. We
 don't need those code sections at all on Mac

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Ticket URL: <https://trac.macports.org/ticket/70824>
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