Cherry-pick of 29438 to R3.1

Fixing invalid message received in nh --get o/p

Skipping sub-nh expansion for composite nh case if the index is -1
in nh utility.

Change-Id: I2bb90d7b1ff16beb088f928ead3e4a6d84f5537d
Closes-Bug: #1670820

utils/nh.c

@@ -292,6 +292,9 @@ vr_nexthop_req_process(void *s_req)
     printf("\n\n");
     if (req->nhr_type == NH_COMPOSITE && command == SANDESH_OP_GET) {
         for (i = 0; i < req->nhr_nh_list_size; i++) {
+            // Skip expanding sub-nh for -1 index
+            if (req->nhr_nh_list[i] == -1)
+                continue;
             vr_nh_op(cl, command, type, req->nhr_nh_list[i], if_id, vrf_id,
                      dst_mac, src_mac, sip, dip, flags);
         }