Remove the Opt_Generics constructor
Remove the Opt_Generics constructor

We no longer advertise that we support the Generics extension,
although we still do accept -XGenerics and -XNoGenerics flags
(but warn that we are ignoring them).

I also remove the even older -fgenerics and -fno-generics flags.

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