yylex_destroy returns a useless int

[Akim Demaille]

The documentation and the code show that yylex_destroy returns an int,
but the former specifies no meaning, and (apparently) neither does the
latter:

| /* %if-c-only SNIP! this currently causes conflicts with the c++ scanner */
| /* yylex_destroy is for both reentrant and non-reentrant scanners. */
| int yylex_destroy  (void)
| {
|     
|     /* Pop the buffer stack, destroying each element. */
|       while(YY_CURRENT_BUFFER){
|               yy_delete_buffer(YY_CURRENT_BUFFER  );
|               YY_CURRENT_BUFFER_LVALUE = NULL;
|               yypop_buffer_state();
|       }
| 
|       /* Destroy the stack itself. */
|       yyfree((yy_buffer_stack) );
|       (yy_buffer_stack) = NULL;
| 
| /* %if-reentrant */
| /* %endif */
|     return 0;
| }
| /* %endif */

Could it be made void?  That would make it easier to "atexit
(yylex_destroy)".