Don't store the token defs in a muscle, just be ready to output it

on command.  Now possible via `symbols'.  Fixes a memory leak.
* src/output.c (token_definitions_output): New.
(output_parser, header_output): Use it.
* src/reader.c (symbols_save): Remove.

src/muscle_tab.c

@@ -58,9 +58,6 @@ muscle_init (void)
   muscle_insert ("stype", "int");
   muscle_insert ("ltype", "yyltype");
 
-  /* Tokens.  */
-  muscle_insert ("tokendef", NULL);
-
   /* Tables.  */
   muscle_insert ("rhs", NULL);
   muscle_insert ("pact", NULL);