Fix Trac #2456: eliminate duplicate bindings when deriving
Fix Trac #2456: eliminate duplicate bindings when deriving

Condsider deriving two overlapping Data declarations for the same type
	deriving instance Data (T A)
	deriving instance Data (T B)

We were getting duplicate bindings for the data-con and tycon auxiliary
bindings for T.  This patch fixes the problem by doing these two decls
the same way as we do con2tag etc.  

(Why might you want such instances; see Trac #2456.)


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