Modules enabling -XCPP but not needing it

[philderbeast]

The -XCPP language extension is pretty intrusive, interfering with other tools that need to parse the source such as HLint, fourmolu and HLS.

It looks like we have plenty of modules enabling -XCPP but not needing it? Can we remove those redundant language pragmas?

$ grep '^#if' --files-without-match $(grep -R --files-with-matches 'LANGUAGE.*CPP' */**/*.hs)
cabal-install/src/Distribution/Client/Check.hs
cabal-install/src/Distribution/Client/CmdOutdated.hs
cabal-install/src/Distribution/Client/CmdPath.hs
cabal-install/src/Distribution/Client/CmdUpdate.hs
cabal-install/src/Distribution/Client/Configure.hs
cabal-install/src/Distribution/Client/FileMonitor.hs
cabal-install/src/Distribution/Client/GenBounds.hs
cabal-install/src/Distribution/Client/IndexUtils.hs
cabal-install/src/Distribution/Client/InstallSymlink.hs
cabal-install/src/Distribution/Client/Main.hs
cabal-install/src/Distribution/Client/Manpage.hs
cabal-install/src/Distribution/Client/ProjectBuilding.hs
cabal-install/src/Distribution/Client/ProjectConfig.hs
cabal-install/src/Distribution/Client/ProjectPlanning.hs
cabal-install/src/Distribution/Client/Sandbox.hs
cabal-install/src/Distribution/Client/Security/HTTP.hs
cabal-install/src/Distribution/Client/Targets.hs
cabal-install/src/Distribution/Deprecated/ParseUtils.hs
cabal-install/src/Distribution/Deprecated/ReadP.hs
cabal-install/tests/UnitTests/Distribution/Client/FileMonitor.hs
cabal-install/tests/UnitTests/Distribution/Client/Glob.hs
cabal-install/tests/UnitTests/Distribution/Client/UserConfig.hs
cabal-install/tests/UnitTests/Distribution/Solver/Modular/QuickCheck.hs
cabal-install/tests/UnitTests/Distribution/Solver/Types/OptionalStanza.hs
Cabal-QuickCheck/src/Test/QuickCheck/GenericArbitrary.hs
Cabal-syntax/src/Distribution/Compat/Binary.hs
Cabal-syntax/src/Distribution/Compat/Exception.hs
Cabal-syntax/src/Distribution/Compat/Graph.hs
Cabal-syntax/src/Distribution/Compat/MonadFail.hs
Cabal-syntax/src/Distribution/Compat/Newtype.hs
Cabal-syntax/src/Distribution/Compat/Prelude.hs
Cabal-syntax/src/Distribution/Compat/Semigroup.hs
Cabal-syntax/src/Distribution/FieldGrammar/Class.hs
Cabal-syntax/src/Distribution/Fields/ParseResult.hs
Cabal-syntax/src/Distribution/PackageDescription/Parsec.hs
Cabal-syntax/src/Distribution/Parsec.hs
Cabal-syntax/src/Distribution/System.hs
Cabal-syntax/src/Distribution/Utils/Generic.hs
Cabal-tests/tests/UnitTests/Distribution/CabalSpecVersion.hs
Cabal-tests/tests/UnitTests/Distribution/Utils/CharSet.hs
Cabal-tests/tests/UnitTests/Distribution/Utils/Structured.hs
cabal-testsuite/main/cabal-tests.hs
cabal-testsuite/PackageTests/Backpack/bkpcabal01/p/P.hs
cabal-testsuite/PackageTests/CabalMacros/Mdl.hs
cabal-testsuite/PackageTests/CmmSources/src/Demo.hs
cabal-testsuite/PackageTests/CmmSourcesDyn/demo/Main.hs
cabal-testsuite/PackageTests/CmmSourcesDyn/src/Demo.hs
cabal-testsuite/PackageTests/CmmSourcesExe/src/Demo.hs
cabal-testsuite/PackageTests/Haddock/CPP.hs
cabal-testsuite/PackageTests/PreProcess/Hsc2HsOptionsCC/Main.hs
cabal-testsuite/PackageTests/Regression/T5386/Foo.hs
cabal-testsuite/src/Test/Cabal/TestCode.hs
Cabal-tree-diff/src/Data/TreeDiff/Instances/Cabal.hs
Cabal-tree-diff/src/Data/TreeDiff/Instances/CabalLanguage.hs
Cabal-tree-diff/src/Data/TreeDiff/Instances/CabalSPDX.hs
Cabal-tree-diff/src/Data/TreeDiff/Instances/CabalVersion.hs
Cabal/src/Distribution/Compat/Async.hs
Cabal/src/Distribution/Compat/ResponseFile.hs
Cabal/src/Distribution/Compat/Stack.hs
Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs
Cabal/src/Distribution/Simple/GHCJS.hs
Cabal/src/Distribution/Simple/Setup.hs
Cabal/src/Distribution/Simple/Setup/Benchmark.hs
Cabal/src/Distribution/Simple/Setup/Build.hs
Cabal/src/Distribution/Simple/Setup/Clean.hs
Cabal/src/Distribution/Simple/Setup/Common.hs
Cabal/src/Distribution/Simple/Setup/Copy.hs
Cabal/src/Distribution/Simple/Setup/Global.hs
Cabal/src/Distribution/Simple/Setup/Haddock.hs
Cabal/src/Distribution/Simple/Setup/Hscolour.hs
Cabal/src/Distribution/Simple/Setup/Install.hs
Cabal/src/Distribution/Simple/Setup/Register.hs
Cabal/src/Distribution/Simple/Setup/Repl.hs
Cabal/src/Distribution/Simple/Setup/SDist.hs
Cabal/src/Distribution/Simple/Setup/Test.hs
Cabal/src/Distribution/Utils/MapAccum.hs
Cabal/src/Distribution/Utils/Progress.hs