Fix Trac #3964: view patterns in DsArrows
Fix Trac #3964: view patterns in DsArrows

Just a missing case; I've eliminated the catch-all so 
that we get a warning next time we extend HsPat

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