Test FlexibleInstance not UndecidableInstances in the ambiguity check
Test FlexibleInstance not UndecidableInstances in the ambiguity check

Fixes Trac #7131

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