Fix Trac #2520: duplicate symbols
Fix Trac #2520: duplicate symbols

The problem here was that were were quantifying over an *External* Name,
which causes no end of confusion.  See Note [Const rule dicts] in DsBinds.

The fix is very easy, I'm happy to say.



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