parrots arrays do not seem to like natives

This explodes using perl6-p: my @j; my int $j = 0; @j.push($j)
Since I dont expect that this will be fixed quickly, I am de-
optimizing the code slightly to make it work on perl6-p.

src/core/metaops.pm

@@ -34,7 +34,7 @@ sub METAOP_CROSS(\op, &reduce) {
             nqp::bindpos($cache, $i, $rpa);
         }
         my int $n = lol.elems - 1;
-        my int $j = 0;
+        my $j = 0;
         my @j;
         my @v;