Fix parsing export lists
Fix parsing export lists

We were accepting
    module ExportCommaComma (id, reverse,,) where
where only 1 trailing comma should be permitted.

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