update all_name_chars comment after 9020ac7cce97dddad51b285fffc31fe4ddf60898 (#3452)

diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index be2d7b2..eee9bfe 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -10,8 +10,7 @@
     void *ce_extras[1];
 } _PyCodeObjectExtra;
 
-/* all_name_chars(s): true iff all chars in s are valid NAME_CHARS */
-
+/* all_name_chars(s): true iff s matches [a-zA-Z0-9_]* */
 static int
 all_name_chars(PyObject *o)
 {