GHC ports overhaul. Merge lang/ghc* ports back into one.

[arrowd]

Summary

• Merge lang/ghc* ports back into one.
• Remove OPTIONS support from bsd.cabal[.options].mk.
• Fix https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=224083
• Add support for building different GHC versions based on GHC_VERSION variable.
• Various cleanups.

[arrowd]

[tcberner]

It would probably make sense to add MOVED entries

[arrowd]

• List removed ports in MOVED file.

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[tcberner]

It looks like the lang/Makefile changes are missing

[tcberner]

With the mentioned change it loosk good to me.

[tcberner]

[01:05:19] [04] [00:00:15] Finished devel/hs-hashable | hs-hashable-1.2.7.0_3,1: Failed: configure

could you verify that that builds fine for you.