Add IGMP type offset definition

Test: TH
Change-Id: Ia81dd5a359b95bc68aa48d30fda08fc69608fcdb
diff --git a/bpf/headers/include/bpf/BpfClassic.h b/bpf/headers/include/bpf/BpfClassic.h
index 81be37d..924f7a3 100644
--- a/bpf/headers/include/bpf/BpfClassic.h
+++ b/bpf/headers/include/bpf/BpfClassic.h
@@ -160,6 +160,9 @@
 #define BPF_LOAD_NETX_RELATIVE_ICMP_TYPE BPF_LOAD_NETX_RELATIVE_L4_U8(0)
 #define BPF_LOAD_NETX_RELATIVE_ICMP_CODE BPF_LOAD_NETX_RELATIVE_L4_U8(1)
 
+// IGMP start with u8 type
+#define BPF_LOAD_NETX_RELATIVE_IGMP_TYPE BPF_LOAD_NETX_RELATIVE_L4_U8(0)
+
 // IPv6 extension headers (HOPOPTS, DSTOPS, FRAG) begin with a u8 nexthdr
 #define BPF_LOAD_NETX_RELATIVE_V6EXTHDR_NEXTHDR BPF_LOAD_NETX_RELATIVE_L4_U8(0)