Remove the need for a static function to call scanner.yylex

First, I tried with "name-prefix" or "api.prefix" but their behaviours change depending whether there is a dot in the provided string! Without a dot, the api.prefix only affects the yylex define. But as soon as I put a dot, or colon, etc, the prefix is used in a lot of other #defines… I agree this is silly ;-)

But this commit compiles & works. And I think these 2 lines are better than the static function.

Michel