beautified code a bit, and add comment about pir::set_vps($meth, $met…

…h_name)

... as requested by pmichaud++
No functional changes.

src/metamodel/Attribute.nqp

@@ -62,9 +62,10 @@ method compose($package) {
         # XXX check there isn't already one...
         my $meth := $!rw ?? pir::find_lex__Ps('accessor_helper_rw') !! pir::find_lex__Ps('accessor_helper_ro');
         my $meth_name := pir::substr__SSi($name, 2);
-        $meth := pir::clone__PP($meth);
+        $meth := pir::clone($meth);
         # introspection looks at the actual sub name, so set it
         # to the value the user expects
+        # set $P0, $S0  is parrot's clunky PIR API for setting the sub name.
         pir::set__vps($meth, $meth_name);
         $package.add_method($package, $meth_name, $meth);
     }