* 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.c

@@ -200,13 +200,8 @@ symbol_user_token_number_set (symbol_t *symbol,
 static void
 symbol_free (symbol_t *this)
 {
-#if 0
-  /* This causes crashes because one string can appear more
-     than once.  */
-  XFREE (this->type_name);
-#endif
-  XFREE (this->tag);
-  XFREE (this);
+  free (this->tag);
+  free (this);
 }