parser/rr: free_rr() is expecting rr_t** parameter

- give the parameter as &r, following the commit
  b40d92962b680ac29dd38ffe3c8f1aa1e39d3a97

parser/parse_rr.c

@@ -138,7 +138,7 @@ static inline int do_parse_rr_body(char *buf, int len, rr_t **head)
 	}
 
  error:
-	if (r) free_rr(r);
+	if (r) free_rr(&r);
 	free_rr(head); /* Free any contacts created so far */
 	return -1;