* src/reader.c (parse_union_decl): Add new obstack union_obstack. Which

will contain `%union' declaration.
(parse_union_decl): Delete #line directive output.
(parse_union_decl): Substitute /attrs_obstack/union_obstack for all
informations about %union.
(parse_union_decl): Copy the union_obstack in the muscle stype.
* src/bison.simple: Add new #line directive.
Add typdef %%stype YYSTYPE.