exprIsHNF should "look through" lets
exprIsHNF should "look through" lets

I can't quite remember when I spotted this, but exprIsHNF (and
similarly exprIsConLike) should ignore enclosing let-bindings,
since they don't affect termination.

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