Check return value of sigaction
Check return value of sigaction

Issue discovered by Coverity scan, CID 43142.

Signed-off-by: Austin Seipp <7ea35d812706d9213868749011af1ed4fa2f6aa0@well-typed.com>

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