[name] Add hb_ot_name_id_predefined_t

Not sure what to do about its docs.

src/hb-ot-name.h

@@ -74,7 +74,7 @@ HB_BEGIN_DECLS
  *
  * Since: 2.0.0
  **/
-enum
+typedef enum
 {
   HB_OT_NAME_ID_COPYRIGHT		= 0,
   HB_OT_NAME_ID_FONT_FAMILY		= 1,
@@ -104,7 +104,7 @@ enum
   HB_OT_NAME_ID_VARIATIONS_PS_PREFIX	= 25,
 
   HB_OT_NAME_ID_INVALID			= 0xFFFF
-};
+} hb_ot_name_id_predefined_t;
 
 typedef unsigned int hb_ot_name_id_t;