array.c: set class

* array.c (rb_ary_uniq): set class of the return value to the receiver
  class.  fix failure in TestArray#test_array_subclass.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43196 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

array.c

@@ -4131,6 +4131,7 @@ rb_ary_uniq(VALUE ary)
 	hash = ary_make_hash(ary);
 	uniq = rb_hash_keys(hash);
     }
+    RBASIC_SET_CLASS(uniq, rb_obj_class(ary));
     ary_recycle_hash(hash);
 
     return uniq;