Removing old ghc* packages

[Thomas Klausner <wiz%NetBSD.org@localhost>]

This is a heads-up that we'll be removing the following packages:

lang/ghc7
lang/ghc80
lang/ghc84
lang/ghc88
lang/ghc810
lang/ghc90

(broken on NetBSD 10) in a week. These packages were previously used
for bootstrapping newer ghc versions. Nowadays the recommended method
is to cross-compile the same, previous, or second-to-last version on a
supported platform.  and keeping these packages working is not
useful. Also, some current Haskell code won't even compile with them.

(Please note that even ghc7 was not bootstrappable from C.)

This was approved by the MAINTAINER pho@.

Cheers,
 Thomas