parser: use %pure-parser instead of %define api.pure

Both bison and byacc support this syntax. Bison manpage says something
about this giving more or less options, but we don't care.

Signed-off-by: Ran Benita <ran234@gmail.com>

src/xkbcomp/parser.y

@@ -46,7 +46,7 @@ _xkbcommon_error(struct YYLTYPE *loc, struct parser_param *param, const char *ms
 %}
 
 %name-prefix    "_xkbcommon_"
-%define         api.pure
+%pure-parser
 %locations
 %lex-param      { struct scanner *scanner }
 %parse-param    { struct parser_param *param }