Fix bug in stg_enter_checkbh
Fix bug in stg_enter_checkbh

This was causing crashes in stm050(ghci), throwto001(ghci), and
possibly more.

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