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

* 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.