thread.c, vm_method.c: avoid inadvertent pin-down

* thread.c (rb_thread_variable_set): get rid of inadvertent dynamic
  symbol pin-down.

* vm_method.c (obj_respond_to): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47004 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

thread.c

@@ -2928,7 +2928,7 @@ rb_thread_variable_set(VALUE thread, VALUE id, VALUE val)
     }
 
     locals = rb_ivar_get(thread, id_locals);
-    return rb_hash_aset(locals, ID2SYM(rb_to_id(id)), val);
+    return rb_hash_aset(locals, rb_to_symbol(id), val);
 }
 
 /*

vm_method.c

@@ -1694,7 +1694,7 @@ obj_respond_to(int argc, VALUE *argv, VALUE obj)
     if (!(id = rb_check_id(&mid))) {
 	if (!rb_method_basic_definition_p(CLASS_OF(obj), idRespond_to_missing)) {
 	    VALUE args[2];
-	    args[0] = ID2SYM(rb_to_id(mid));
+	    args[0] = rb_to_symbol(mid);
 	    args[1] = priv;
 	    return rb_funcall2(obj, idRespond_to_missing, 2, args);
 	}