Fix Num:U++
Fix Num:U++

The postfix increment on a :U type is meant to return zero, but here it
returns an Int zero instead of a Num zero.

jonathanstowe/rakudo,tbrowder/rakudo,rakudo/rakudo,nbrown/rakudo,lucasbuchala/rakudo,sjn/rakudo,tbrowder/rakudo,nbrown/rakudo,jonathanstowe/rakudo,usev6/rakudo,lucasbuchala/rakudo,salortiz/rakudo,salortiz/rakudo,MasterDuke17/rakudo,salortiz/rakudo,tony-o/rakudo,softmoth/rakudo,samcv/rakudo,jonathanstowe/rakudo,nbrown/rakudo,labster/rakudo,tony-o/rakudo,MasterDuke17/rakudo,tony-o/rakudo,raydiak/rakudo,rakudo/rakudo,usev6/rakudo,sjn/rakudo,softmoth/rakudo,labster/rakudo,labster/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tony-o/rakudo,MasterDuke17/rakudo,awwaiid/rakudo,awwaiid/rakudo,nbrown/rakudo,rakudo/rakudo,MasterDuke17/rakudo,tony-o/rakudo,Gnouc/rakudo,nbrown/rakudo,salortiz/rakudo,raydiak/rakudo,usev6/rakudo,raydiak/rakudo,lucasbuchala/rakudo,softmoth/rakudo,raydiak/rakudo,Gnouc/rakudo,samcv/rakudo,tbrowder/rakudo,samcv/rakudo,awwaiid/rakudo,jonathanstowe/rakudo,labster/rakudo,labster/rakudo,samcv/rakudo,salortiz/rakudo,awwaiid/rakudo,jonathanstowe/rakudo,samcv/rakudo,tbrowder/rakudo,lucasbuchala/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,rakudo/rakudo,nbrown/rakudo,Gnouc/rakudo,Gnouc/rakudo,awwaiid/rakudo,softmoth/rakudo,MasterDuke17/rakudo,tony-o/rakudo,sjn/rakudo,sjn/rakudo,salortiz/rakudo,labster/rakudo,sjn/rakudo,softmoth/rakudo,Gnouc/rakudo,usev6/rakudo,rakudo/rakudo,tbrowder/rakudo,rakudo/rakudo,usev6/rakudo