Add negative offset checks to read-int/write-int
Add negative offset checks to read-int/write-int

To at least make sure we don't release a version of these that do allow
negative offsets.

salortiz/rakudo,labster/rakudo,nbrown/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,nbrown/rakudo,MasterDuke17/rakudo,rakudo/rakudo,salortiz/rakudo,Gnouc/rakudo,rakudo/rakudo,tony-o/rakudo,MasterDuke17/rakudo,rakudo/rakudo,Gnouc/rakudo,softmoth/rakudo,nbrown/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tony-o/rakudo,tony-o/rakudo,nbrown/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,labster/rakudo,softmoth/rakudo,MasterDuke17/rakudo,softmoth/rakudo,tony-o/rakudo,softmoth/rakudo,nbrown/rakudo,salortiz/rakudo,tbrowder/rakudo,labster/rakudo,tbrowder/rakudo,labster/rakudo,rakudo/rakudo,salortiz/rakudo,nbrown/rakudo,Gnouc/rakudo,tbrowder/rakudo,tony-o/rakudo,tony-o/rakudo,Gnouc/rakudo,Gnouc/rakudo,labster/rakudo,Gnouc/rakudo,labster/rakudo,tbrowder/rakudo,salortiz/rakudo,softmoth/rakudo,rakudo/rakudo,rakudo/rakudo