extensions: add const qualifiers in print/save functions

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/extensions/libxt_rateest.c b/extensions/libxt_rateest.c
index 3cff07d..9f3a436 100644
--- a/extensions/libxt_rateest.c
+++ b/extensions/libxt_rateest.c
@@ -332,7 +332,8 @@
 }
 
 static void
-rateest_print_mode(struct xt_rateest_match_info *info, const char *prefix)
+rateest_print_mode(const struct xt_rateest_match_info *info,
+                   const char *prefix)
 {
 	if (info->flags & XT_RATEEST_MATCH_INVERT)
 		printf("! ");
@@ -355,7 +356,7 @@
 static void
 rateest_print(const void *ip, const struct xt_entry_match *match, int numeric)
 {
-	struct xt_rateest_match_info *info = (void *)match->data;
+	const struct xt_rateest_match_info *info = (const void *)match->data;
 
 	printf("rateest match ");
 
@@ -405,7 +406,7 @@
 static void
 rateest_save(const void *ip, const struct xt_entry_match *match)
 {
-	struct xt_rateest_match_info *info = (void *)match->data;
+	const struct xt_rateest_match_info *info = (const void *)match->data;
 
 	if (info->flags & XT_RATEEST_MATCH_REL) {
 		printf("--rateest1 %s ", info->name1);