[MacPorts] #51310: ImageMagick: update to 7.x

[MacPorts]

#51310: ImageMagick: update to 7.x
--------------------------+------------------------
  Reporter:  mopihopi     |      Owner:  ryandesign
      Type:  update       |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:               |   Keywords:
      Port:  ImageMagick  |
--------------------------+------------------------

Comment (by joostdekeijzer):

 Replying to [comment:32 kencu]:
 > I am not seeing in your branch how you handled having the two different
 versions installed at the same time, or how a port that wants to use one
 or the other, via say pkgconfig, can specify that reliably.
 >
 > Perhaps I am missing the "magic" ;)

 Well, if it's "magic" it's recycled from others ;-) I think I copied this
 from either MariaDB or Python port files?

 By setting the `--mandir`, `--libdir` and `--binddir` configure args all
 port related files are put into the directories configured.

 For ImageeMagic-7 that would be: `/opt/local/share/man/ImageMagick-7/`,
 `/opt/local/lib/ImageMagick-7/` and `/opt/local/lib/ImageMagick-7/bin/`
 respectively. For ImageMagick-6 it's comparable.

 This also means that the pkgconfig files are in
 `/opt/local/lib/ImageMagick-7/pkgconfig/` so when compiling against
 ImageMagick-7 you must set the pkgconfig search path to that directory.
 There are several options here:
 * set, append or prepend `configure.pkg_config_path` (`configure
 .pkg_config_path-append`, `configure.pkg_config_path-prepend`) eg.
 ''gimp2'', ''mlt'' or ''MyPaint'' ports
 * set `configure.env PKG_CONFIG_PATH` eg. ''curl'' port
 * set `build.env PKG_CONFIG_PATH` eg. ''py-cartopy'' port

 And I expect many more ways to do this?

 Because the current ImageMagick partially uses a ImageMagic-6 "namespace"
 I decided to create a new port (ImageMagick-6) which sets all directories.

 Let me know if you have any other questions :)

-- 
Ticket URL: <https://trac.macports.org/ticket/51310#comment:33>
MacPorts <https://www.macports.org/>
Ports system for macOS