Delete ghctags cabal file

It came back to life in 381c3ae3 by
mistake.

utils/ghctags/ghctags.cabal

-Name: ghctags
-Version: 0.1
-Copyright: XXX
-License: BSD3
--- XXX License-File: LICENSE
-Author: XXX
-Maintainer: XXX
-Synopsis: A simple generator of vi- and emacs-compatible TAGS files.
-Description: XXX
-Category: Development
-build-type: Simple
-cabal-version: >=1.10
-
-Executable ghctags
-    Default-Language: Haskell2010
-
-    Main-Is: Main.hs
-
-    Build-Depends: base       >= 4   && < 5,
-                   containers,
-                   Cabal      >= 3.0 && <3.1,
-                   ghc
-