Bug 13562

We have found that it is sometimes useful for lex to have YYERRCODE
defined for reporting scanning errors back to yacc.  The first section
of the patch emits the defined value into y.tab.h 

The second section of the patch allows for a user specified parameter
to 'yyparse()', in a manner similar to that used by bison.  The names
are consistent with the bison implementation but this one also allows
the type of the parameter to be specified.

We generate an old-style function header for 'yyparse()' in the y.tab.c
outfile.   Generally, we supplement this with a hand-coded prototype
in a shared header file.

for a desired prototype of:

    int yyparse __P((struct yyresult *));


 ... compile like this:

    yacc -dv grammar.y
    cc -c -DYYPARSE_PARAM_TYPE="struct yyresult *" -DYYPARSE_PARAM="parm" \
       y.tab.c

 ... use like this:

${
#include "usrtypes.h"
#include "usrproto.h"
}$

%token NUMBER

%%

goal : NUMBER
       {
               parm->value = yylval; 
       }
;

If YYPARSE_PARAM_TYPE isn't specified then "void *" is the default type

If YYPARSE_PARAM is not specified then the generated code behaves exactly
as traditional byacc.

How-To-Repeat: 
Apply the patch :-)