ghc-filesystem: A plan for updating to the version after 1.5.14

[ryandesign (Ryan Carsten Schmidt)]

Ports using ghc-filesystem 1.5.14 can't compile on macOS 10.12 or earlier because it uses utimensat which was introduced in macOS 10.13. A workaround is to use legacysupport. See #68438.

This problem was fixed in ghc-filesystem nine months ago but there has not yet been a new release. I've filed an issue asking them to make a new release: ​https://github.com/gulrak/filesystem/issues/182

Once this happens and MacPorts updates to the new release, the inclusion of legacysupport in all of the ports that depend on ghc-filesystem should be reverted since it should no longer be necessary. The revision of all of those ports should also be increased so that they rebuild with the new ghc-filesystem.