settings: Include generated header after others

Newer Bison versions declare the parser function in the header, which
requires custom types.

src/libstrongswan/settings/settings_lexer.l

@@ -14,10 +14,10 @@
  * for more details.
  */
 
-#include "settings_parser.h"
-
 #include <utils/parser_helper.h>
 
+#include "settings_parser.h"
+
 bool settings_parser_open_next_file(parser_helper_t *ctx);
 
 static void include_files(parser_helper_t *ctx);