detect/icmp: require real packet in signature

Fixes: 956c8bebd1 ("detect/prefilter: use sig mask to exclude pkt engines")

src/detect-icmp-seq.c

@@ -249,6 +249,7 @@ static int DetectIcmpSeqSetup (DetectEngineCtx *de_ctx, Signature *s, const char
                 de_ctx, s, DETECT_ICMP_SEQ, (SigMatchCtx *)iseq, DETECT_SM_LIST_MATCH) == NULL) {
         goto error;
     }
+    s->flags |= SIG_FLAG_REQUIRE_PACKET;
 
     return 0;