MacVim @8.2.snapshot171: Add newer ruby variants (and possibly remove old ones?)

[cooljeanius (Eric Gallager)]

Currently the newest ruby variant for MacVim is ruby25, however, there are newer ruby ports than that that don't have variants for them yet. If adding new ruby variants would result in there being too many of them, I'd be ok with removing some of the older ones to balance it out.

[cooljeanius (Eric Gallager)]

Note that I was prompted to file this issue because my MacVim suddenly stopped being able to open files after an upgrade. Running it in a debugger revealed messages like this:

Process 36425 launched: '/Applications/MacPorts/MacVim.app/Contents/MacOS/MacVim' (x86_64)
dyld: Library not loaded: @executable_path/../lib/libruby.2.5.dylib
  Referenced from: /Applications/MacPorts/MacVim.app/Contents/MacOS/Vim
  Reason: image not found

Presumably this was because my ruby25 is installed with the +relative variant:

$ port installed ruby25
The following ports are currently installed:
  ruby25 @2.5.9_0+doc+gmp+relative (active)
$

Installing MacVim without a ruby variant allowed it to work again. However, I'd like to have a ruby variant back eventually, and it'd be good to make it a newer one while I'm at it.