* src/symtab.c (symbol_free): Remove dead deactivated code:

type_name are properly removed.
Don't use XFREE to free items that cannot be NULL.
* src/struniq.h, src/struniq.c: New.
* src/main.c (main): Initialize/free struniqs.
* src/parse-gram.y (%union): Add astruniq member.
(yyprint): Adjust.
* src/scan-gram.l (<{tag}>): Return a struniq.
Free the obstack bit that used to store it.
* src/symtab.h (symbol_t): The 'type_name' member is a struniq.

src/symtab.h

@@ -22,6 +22,7 @@
 #ifndef SYMTAB_H_
 # define SYMTAB_H_
 
+# include "struniq.h"
 # include "location.h"
 # include "assoc.h"
 
@@ -52,7 +53,7 @@ struct symbol_s
   location_t location;
 
   /* Its %type and associated printer and destructor.  */
-  char *type_name;
+  struniq_t type_name;
   char *destructor;
   location_t destructor_location;
   char *printer;