Fixes warning on compilation of ip6tables matches/targets

This changes the type of arguments as follows
- ip6t_ip6 * -> void *
- ip6t_entry * -> void *
diff --git a/extensions/libip6t_LOG.c b/extensions/libip6t_LOG.c
index ad65bd5..7fdbc0c 100644
--- a/extensions/libip6t_LOG.c
+++ b/extensions/libip6t_LOG.c
@@ -110,7 +110,7 @@
    ate an option */
 static int
 parse(int c, char **argv, int invert, unsigned int *flags,
-      const struct ip6t_entry *entry,
+      const void *entry,
       struct xt_entry_target **target)
 {
 	struct ip6t_log_info *loginfo = (struct ip6t_log_info *)(*target)->data;
@@ -206,7 +206,7 @@
 
 /* Prints out the targinfo. */
 static void
-print(const struct ip6t_ip6 *ip,
+print(const void *ip,
       const struct xt_entry_target *target,
       int numeric)
 {
@@ -247,7 +247,7 @@
 
 /* Saves the union ip6t_targinfo in parsable form to stdout. */
 static void
-save(const struct ip6t_ip6 *ip, const struct xt_entry_target *target)
+save(const void *ip, const struct xt_entry_target *target)
 {
 	const struct ip6t_log_info *loginfo
 		= (const struct ip6t_log_info *)target->data;