Cabal revisions of llvm-hs-4.2.0

Hackage metadata revisions edit the .cabal file after upload; each diff below is one revision.

 name: llvm-hs version: 4.2.0+x-revision: 1 license: BSD3 license-file: LICENSE author: Anthony Cowley, Stephen Diehl, Moritz Kiefer <moritz.kiefer@purelyfunctional.org>, Benjamin S. Scarlet  custom-setup   setup-depends: base-               , Cabal+               , Cabal <2                , containers  library-  build-tools: llvm-config+  build-tools: llvm-config, hsc2hs   ghc-options: -Wall -fno-warn-name-shadowing -fno-warn-orphans -fno-warn-incomplete-patterns -fno-warn-missing-signatures -fno-warn-unused-matches   if flag(semigroups)     build-depends: