simplify the handling of <> and <*>'s code_props.

Currently they are treated in separated variables, contrary to other
<TYPE> code_props.  This duplicates code (and messages for translators)
uselessly, as demonstrated by the fact that thanks to this patch, now
useless <*> and <> code_props are reported like the others.

* src/parse-gram.y (generic_symlist_item): Treat "<*>" and "<>" as regular
type tags.
* src/symlist.h, src/symlist.c (symbol_list_default_tagged_new)
(symbol_list_default_tagless_new,SYMLIST_DEFAULT_TAGGED)
(SYMLIST_DEFAULT_TAGLESS): Remove.
* src/symtab.h, src/symtab.c (default_tagged_code_props)
(default_tagless_code_props, default_tagged_code_props_set)
(default_tagless_code_props_set): Remove.
(symbol_code_props_get): Default to <*> or <>'s code_props.

* tests/actions.at: Complete expected errors: there are new warnings.
* tests/input.at: Likewise.
(Useless printers or destructors): Extend.

src/symlist.h

@@ -34,8 +34,8 @@ typedef struct symbol_list
    * \c <>.
    */
   enum {
-    SYMLIST_SYMBOL, SYMLIST_TYPE,
-    SYMLIST_DEFAULT_TAGGED, SYMLIST_DEFAULT_TAGLESS
+    SYMLIST_SYMBOL,
+    SYMLIST_TYPE
   } content_type;
   union {
     /**
@@ -88,11 +88,6 @@ symbol_list *symbol_list_sym_new (symbol *sym, location loc);
 /** Create a list containing \c type_name at \c loc.  */
 symbol_list *symbol_list_type_new (uniqstr type_name, location loc);
 
-/** Create a list containing a \c <*> at \c loc.  */
-symbol_list *symbol_list_default_tagged_new (location loc);
-/** Create a list containing a \c <> at \c loc.  */
-symbol_list *symbol_list_default_tagless_new (location loc);
-
 /** Print this list.
 
   \pre For every node \c n in the list, <tt>n->content_type =