Only uninstall signal handlers if they were actually installed (#9068)
Only uninstall signal handlers if they were actually installed (#9068)

Submitted by: tomgr

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