Add <netinet/igmp.h>.

Test: treehugger
Change-Id: I9252275173eab0219a0202463c6accba809a8e11
diff --git a/tests/Android.bp b/tests/Android.bp
index 9aca488..7769110 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -430,6 +430,7 @@
         "netdb_test.cpp",
         "net_if_test.cpp",
         "netinet_ether_test.cpp",
+        "netinet_igmp_test.cpp",
         "netinet_in_test.cpp",
         "netinet_ip_icmp_test.cpp",
         "netinet_udp_test.cpp",