[MacPorts] #71389: libproxy: move vala bindings to a variant or subport to reduce dependencies count

[MacPorts]

#71389: libproxy: move vala bindings to a variant or subport to reduce dependencies
count
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  Reporter:  jleroy       |      Owner:  (none)
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:
      Port:  libproxy     |
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Comment (by ryandesign):

 Some fairly simple uses of `subport` are in my ports file, e2fsprogs,
 unicode, and youtube-dl. Observe not only the `subport` block but also
 uses of the `${subport}` variable.

 If you can figure out how to tell the libproxy build system to build and
 install only the vala bindings, that's best. It might happen via configure
 args, using a different build/destroot directory (the libcomerr subport of
 the e2fsprogs port uses this strategy) or build/destroot target, and/or
 patching the build system. Worst case, you have to build all of libproxy
 again just to get the vala bindings built, and then in a post-destroot
 block you'll delete everything other than the vala bindings (the libmagic
 subport of the file port uses this strategy).

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Ticket URL: <https://trac.macports.org/ticket/71389#comment:8>
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