Fix crash with +RTS -xc  (occasional cgrun057(profthreaded) failure)
Fix crash with +RTS -xc  (occasional cgrun057(profthreaded) failure)

Don't try to print a stack trace from raiseAsync() when there's no
exception - we might just be deleting the thread, or suspending
duplicate work.

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