Fix argument for call to archetypes

This buglet sneaked in with 71de223 where an optional positional
parameter for archetypes was introduced. Similar to other methods
of the metamodel API the first argument should be the object that
HOW was invoked upon.

src/Perl6/Metamodel/CurriedRoleHOW.nqp

@@ -164,7 +164,7 @@ class Perl6::Metamodel::CurriedRoleHOW
                 $_);
         }
         for %!named_args {
-            %new_named{$_.key} := $_.value.HOW.archetypes($_).generic ??
+            %new_named{$_.key} := $_.value.HOW.archetypes($_.value).generic ??
                 $_.value.HOW.instantiate_generic($_.value, $type_env) !!
                 $_.value;
         }