Make any bigint for pos a failure for index/rindex
Make any bigint for pos a failure for index/rindex

This further evades the difference between MoarVM and JVM for
nqp::unbox_i of bigints (fails on MoarVM, silently truncates on JVM)

azawawi/rakudo,lucasbuchala/rakudo,tony-o/rakudo,ab5tract/rakudo,labster/rakudo,salortiz/rakudo,labster/rakudo,jonathanstowe/rakudo,salortiz/rakudo,rakudo/rakudo,tony-o/rakudo,labster/rakudo,MasterDuke17/rakudo,softmoth/rakudo,Gnouc/rakudo,tbrowder/rakudo,tbrowder/rakudo,tbrowder/rakudo,nbrown/rakudo,samcv/rakudo,MasterDuke17/rakudo,raydiak/rakudo,dankogai/rakudo,rakudo/rakudo,raydiak/rakudo,usev6/rakudo,ugexe/rakudo,salortiz/rakudo,lucasbuchala/rakudo,samcv/rakudo,usev6/rakudo,ungrim97/rakudo,azawawi/rakudo,awwaiid/rakudo,awwaiid/rakudo,Gnouc/rakudo,azawawi/rakudo,MasterDuke17/rakudo,LLFourn/rakudo,ungrim97/rakudo,sjn/rakudo,dankogai/rakudo,rakudo/rakudo,ugexe/rakudo,Gnouc/rakudo,lucasbuchala/rakudo,nbrown/rakudo,jonathanstowe/rakudo,tony-o/rakudo,awwaiid/rakudo,labster/rakudo,zostay/rakudo,sjn/rakudo,MasterDuke17/rakudo,azawawi/rakudo,ab5tract/rakudo,usev6/rakudo,tony-o/rakudo,paultcochrane/rakudo,ungrim97/rakudo,rakudo/rakudo,nbrown/rakudo,b2gills/rakudo,dankogai/rakudo,LLFourn/rakudo,b2gills/rakudo,tbrowder/rakudo,samcv/rakudo,ungrim97/rakudo,labster/rakudo,ab5tract/rakudo,ab5tract/rakudo,softmoth/rakudo,zostay/rakudo,zostay/rakudo,LLFourn/rakudo,b2gills/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,ab5tract/rakudo,tony-o/rakudo,salortiz/rakudo,nbrown/rakudo,LLFourn/rakudo,ugexe/rakudo,softmoth/rakudo,nbrown/rakudo,samcv/rakudo,salortiz/rakudo,ugexe/rakudo,samcv/rakudo,paultcochrane/rakudo,raydiak/rakudo,nbrown/rakudo,MasterDuke17/rakudo,raydiak/rakudo,salortiz/rakudo,tony-o/rakudo,azawawi/rakudo,zostay/rakudo,ugexe/rakudo,usev6/rakudo,sjn/rakudo,paultcochrane/rakudo,awwaiid/rakudo,jonathanstowe/rakudo,tbrowder/rakudo,jonathanstowe/rakudo,softmoth/rakudo,paultcochrane/rakudo,sjn/rakudo,tbrowder/rakudo,usev6/rakudo,softmoth/rakudo,ungrim97/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,sjn/rakudo,rakudo/rakudo,Gnouc/rakudo,jonathanstowe/rakudo,dankogai/rakudo,b2gills/rakudo,awwaiid/rakudo,labster/rakudo,LLFourn/rakudo,b2gills/rakudo,dankogai/rakudo,paultcochrane/rakudo,MasterDuke17/rakudo,rakudo/rakudo