[NETFILTER]: annotate xtables targets with const and remove casts

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/xt_tcpmss.c b/net/netfilter/xt_tcpmss.c
index d7a5b27..6771bf0 100644
--- a/net/netfilter/xt_tcpmss.c
+++ b/net/netfilter/xt_tcpmss.c
@@ -31,9 +31,11 @@
           bool *hotdrop)
 {
 	const struct xt_tcpmss_match_info *info = matchinfo;
-	struct tcphdr _tcph, *th;
+	const struct tcphdr *th;
+	struct tcphdr _tcph;
 	/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
-	u8 _opt[15 * 4 - sizeof(_tcph)], *op;
+	const u_int8_t *op;
+	u8 _opt[15 * 4 - sizeof(_tcph)];
 	unsigned int i, optlen;
 
 	/* If we don't have the whole header, drop packet. */