[MacPorts] #71940: Allow legacy-support to cover Frameworks

[MacPorts]

#71940: Allow legacy-support to cover Frameworks
-------------------------+----------------------------
 Reporter:  fhgwright    |      Owner:  fhgwright
     Type:  enhancement  |     Status:  assigned
 Priority:  Low          |  Milestone:
Component:  ports        |    Version:
 Keywords:               |       Port:  legacy-support
-------------------------+----------------------------
 There's some interest in expanding `legacy-support`'s mechanism to apply
 to Frameworks as well.  This is not just a matter of dropping more wrapper
 headers into the existing tree, since each Framework has its own tree, and
 anything in `legacy-support` should parallel that, including only being
 applied when explicitly and separately requested.  In particular,
 providing a wrapper header when the underlying header is missing
 (including just by its path not being included) could cause confusion by
 causing `__has_include()` to succeed and then the possibly resulting
 `include_next` to fail.

 This is mainly just a matter of figuring out a suitable scheme.

-- 
Ticket URL: <https://trac.macports.org/ticket/71940>
MacPorts <https://www.macports.org/>
Ports system for macOS