Make the option structures const.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
diff --git a/extensions/libipt_ULOG.c b/extensions/libipt_ULOG.c
index 88fc16d..cc65bba 100644
--- a/extensions/libipt_ULOG.c
+++ b/extensions/libipt_ULOG.c
@@ -44,7 +44,7 @@
 	       IPTABLES_VERSION);
 }
 
-static struct option opts[] = {
+static const struct option opts[] = {
 	{"ulog-nlgroup", 1, 0, '!'},
 	{"ulog-prefix", 1, 0, '#'},
 	{"ulog-cprange", 1, 0, 'A'},