Merge pull request #3047 from ezyang/cabal-ghcup

Cabal/Cabal.cabal

Cabal/Distribution/InstalledPackageInfo.hs

Cabal/Distribution/Package.hs

Cabal/Distribution/Simple/Bench.hs

Cabal/Distribution/Simple/Build.hs

Cabal/Distribution/Simple/Build/Macros.hs

Cabal/Distribution/Simple/BuildPaths.hs

Cabal/Distribution/Simple/Compiler.hs

Cabal/Distribution/Simple/Configure.hs

Cabal/Distribution/Simple/GHC.hs

Cabal/Distribution/Simple/GHC/IPI641.hs

Cabal/Distribution/Simple/GHC/IPI642.hs

Cabal/Distribution/Simple/GHC/IPIConvert.hs

Cabal/Distribution/Simple/GHC/Internal.hs

Cabal/Distribution/Simple/GHCJS.hs

Cabal/Distribution/Simple/Haddock.hs

Cabal/Distribution/Simple/InstallDirs.hs

Cabal/Distribution/Simple/JHC.hs

Cabal/Distribution/Simple/LHC.hs

Cabal/Distribution/Simple/LocalBuildInfo.hs