Paranoid integer overflow check in osGetMBlocks
Paranoid integer overflow check in osGetMBlocks

Signed-off-by: Austin Seipp <48c905ac3851f382b914247d97dd93273d5ff555@pobox.com>

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