Simplify PprTyThing
Simplify PprTyThing

In particular, don't import GHC (a historical hangover), which
makes this module live much lower down in the module hierarchy.

This in turn means we can call it from TcRnDriver

snoyberg/ghc,vTurbine/ghc,da-x/ghc,vTurbine/ghc,TomMD/ghc,anton-dessiatov/ghc,christiaanb/ghc,holzensp/ghc,lukexi/ghc-7.8-arm64,holzensp/ghc,AlexanderPankiv/ghc,sdiehl/ghc,tibbe/ghc,urbanslug/ghc,snoyberg/ghc,mcschroeder/ghc,ghc-android/ghc,anton-dessiatov/ghc,oldmanmike/ghc,lukexi/ghc,ml9951/ghc,ml9951/ghc,GaloisInc/halvm-ghc,AlexanderPankiv/ghc,nkaretnikov/ghc,sgillespie/ghc,vikraman/ghc,ryantm/ghc,elieux/ghc,acowley/ghc,AlexanderPankiv/ghc,ezyang/ghc,sdiehl/ghc,lukexi/ghc-7.8-arm64,tjakway/ghcjvm,mcschroeder/ghc,spacekitteh/smcghc,mettekou/ghc,sgillespie/ghc,oldmanmike/ghc,jstolarek/ghc,acowley/ghc,shlevy/ghc,hferreiro/replay,da-x/ghc,forked-upstream-packages-for-ghcjs/ghc,siddhanathan/ghc,nkaretnikov/ghc,holzensp/ghc,fmthoma/ghc,lukexi/ghc,lukexi/ghc,da-x/ghc,forked-upstream-packages-for-ghcjs/ghc,gcampax/ghc,shlevy/ghc,siddhanathan/ghc,bitemyapp/ghc,mcschroeder/ghc,vTurbine/ghc,gridaphobe/ghc,forked-upstream-packages-for-ghcjs/ghc,nkaretnikov/ghc,oldmanmike/ghc,oldmanmike/ghc,nkaretnikov/ghc,sgillespie/ghc,nathyong/microghc-ghc,ghc-android/ghc,oldmanmike/ghc,shlevy/ghc,ezyang/ghc,elieux/ghc,GaloisInc/halvm-ghc,gcampax/ghc,christiaanb/ghc,frantisekfarka/ghc-dsi,anton-dessiatov/ghc,elieux/ghc,nathyong/microghc-ghc,acowley/ghc,green-haskell/ghc,gridaphobe/ghc,nkaretnikov/ghc,olsner/ghc,vTurbine/ghc,ryantm/ghc,lukexi/ghc,lukexi/ghc-7.8-arm64,ryantm/ghc,wxwxwwxxx/ghc,nathyong/microghc-ghc,ezyang/ghc,ghc-android/ghc,jstolarek/ghc,vikraman/ghc,hferreiro/replay,wxwxwwxxx/ghc,tibbe/ghc,nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,olsner/ghc,siddhanathan/ghc,gcampax/ghc,olsner/ghc,spacekitteh/smcghc,AlexanderPankiv/ghc,tjakway/ghcjvm,hferreiro/replay,ryantm/ghc,ezyang/ghc,nushio3/ghc,ml9951/ghc,gridaphobe/ghc,spacekitteh/smcghc,mcschroeder/ghc,mettekou/ghc,urbanslug/ghc,sgillespie/ghc,tibbe/ghc,mfine/ghc,christiaanb/ghc,GaloisInc/halvm-ghc,TomMD/ghc,nkaretnikov/ghc,wxwxwwxxx/ghc,gcampax/ghc,acowley/ghc,wxwxwwxxx/ghc,elieux/ghc,bitemyapp/ghc,holzensp/ghc,anton-dessiatov/ghc,mfine/ghc,snoyberg/ghc,da-x/ghc,sdiehl/ghc,shlevy/ghc,tjakway/ghcjvm,jstolarek/ghc,sgillespie/ghc,vikraman/ghc,tibbe/ghc,bitemyapp/ghc,olsner/ghc,acowley/ghc,fmthoma/ghc,sgillespie/ghc,oldmanmike/ghc,ghc-android/ghc,jstolarek/ghc,mettekou/ghc,vikraman/ghc,sgillespie/ghc,spacekitteh/smcghc,frantisekfarka/ghc-dsi,frantisekfarka/ghc-dsi,elieux/ghc,mettekou/ghc,forked-upstream-packages-for-ghcjs/ghc,tjakway/ghcjvm,da-x/ghc,vTurbine/ghc,bitemyapp/ghc,fmthoma/ghc,lukexi/ghc-7.8-arm64,vikraman/ghc,nathyong/microghc-ghc,fmthoma/ghc,siddhanathan/ghc,ezyang/ghc,gcampax/ghc,wxwxwwxxx/ghc,nushio3/ghc,urbanslug/ghc,TomMD/ghc,ezyang/ghc,ml9951/ghc,jstolarek/ghc,mfine/ghc,ryantm/ghc,mcschroeder/ghc,anton-dessiatov/ghc,AlexanderPankiv/ghc,da-x/ghc,AlexanderPankiv/ghc,hferreiro/replay,christiaanb/ghc,hferreiro/replay,TomMD/ghc,tibbe/ghc,TomMD/ghc,ml9951/ghc,lukexi/ghc-7.8-arm64,GaloisInc/halvm-ghc,anton-dessiatov/ghc,olsner/ghc,vTurbine/ghc,shlevy/ghc,ml9951/ghc,gcampax/ghc,sdiehl/ghc,nushio3/ghc,nathyong/microghc-ghc,green-haskell/ghc,gcampax/ghc,mettekou/ghc,tjakway/ghcjvm,hferreiro/replay,christiaanb/ghc,shlevy/ghc,olsner/ghc,forked-upstream-packages-for-ghcjs/ghc,urbanslug/ghc,mettekou/ghc,bitemyapp/ghc,siddhanathan/ghc,gridaphobe/ghc,sdiehl/ghc,olsner/ghc,christiaanb/ghc,snoyberg/ghc,vTurbine/ghc,snoyberg/ghc,nathyong/microghc-ghc,green-haskell/ghc,nushio3/ghc,tjakway/ghcjvm,mcschroeder/ghc,nushio3/ghc,wxwxwwxxx/ghc,siddhanathan/ghc,mettekou/ghc,mfine/ghc,green-haskell/ghc,fmthoma/ghc,vikraman/ghc,acowley/ghc,fmthoma/ghc,ghc-android/ghc,acowley/ghc,green-haskell/ghc,oldmanmike/ghc,mfine/ghc,anton-dessiatov/ghc,mcschroeder/ghc,frantisekfarka/ghc-dsi,vikraman/ghc,snoyberg/ghc,da-x/ghc,nushio3/ghc,gridaphobe/ghc,hferreiro/replay,GaloisInc/halvm-ghc,nushio3/ghc,lukexi/ghc,christiaanb/ghc,elieux/ghc,AlexanderPankiv/ghc,ghc-android/ghc,GaloisInc/halvm-ghc,spacekitteh/smcghc,urbanslug/ghc,mfine/ghc,tjakway/ghcjvm,nkaretnikov/ghc,TomMD/ghc,TomMD/ghc,urbanslug/ghc,GaloisInc/halvm-ghc,ezyang/ghc,wxwxwwxxx/ghc,sdiehl/ghc,elieux/ghc,ml9951/ghc,sdiehl/ghc,shlevy/ghc,urbanslug/ghc,holzensp/ghc,frantisekfarka/ghc-dsi,forked-upstream-packages-for-ghcjs/ghc,fmthoma/ghc,siddhanathan/ghc,snoyberg/ghc,ml9951/ghc,mfine/ghc,gridaphobe/ghc,gridaphobe/ghc,ghc-android/ghc