Fixed build failures with older versions of Bison

Older versions of Bison don't include the yyparse function in the generated
header and use deprecated options.

server/modules/filter/dbfwfilter/dbfwfilter.c

@@ -85,6 +85,11 @@
 #include <ruleparser.yy.h>
 #include <lex.yy.h>
 
+/** Older versions of Bison don't include the parsing function in the header */
+#ifndef dbfw_yyparse
+int dbfw_yyparse(void*);
+#endif
+
 MODULE_INFO info =
 {
     MODULE_API_FILTER,

server/modules/filter/dbfwfilter/ruleparser.y

@@ -28,10 +28,10 @@
 %}
 
 /** We need a reentrant scanner so no global variables are used */
-%define api.pure full
+%pure-parser
 
 /** Prefix all functions */
-%name-prefix "dbfw_yy"
+%name-prefix="dbfw_yy"
 
 /** The pure parser requires one extra parameter */
 %parse-param {void* scanner}