Always include <sys/cdefs.h> first.

Otherwise you can't be sure that things like __BIONIC__ work.

Change-Id: Ic5e59988b69419828c3b1a97332c7e2ab58e09a1
diff --git a/libc/include/netinet/icmp6.h b/libc/include/netinet/icmp6.h
index 2b237a8..ebd9f6c 100644
--- a/libc/include/netinet/icmp6.h
+++ b/libc/include/netinet/icmp6.h
@@ -65,9 +65,10 @@
 #ifndef _NETINET_ICMP6_H_
 #define _NETINET_ICMP6_H_
 
-#include <netinet/in.h> /* android-added: glibc source compatibility. */
 #include <sys/cdefs.h>
 
+#include <netinet/in.h> /* android-added: glibc source compatibility. */
+
 #define ICMPV6_PLD_MAXLEN	1232	/* IPV6_MMTU - sizeof(struct ip6_hdr)
 					   - sizeof(struct icmp6_hdr) */
 
diff --git a/libc/include/netinet/in.h b/libc/include/netinet/in.h
index 163e614..d4ce302 100644
--- a/libc/include/netinet/in.h
+++ b/libc/include/netinet/in.h
@@ -28,9 +28,10 @@
 
 #pragma once
 
+#include <sys/cdefs.h>
+
 #include <endian.h>
 #include <netinet/in6.h>
-#include <sys/cdefs.h>
 #include <sys/socket.h>
 
 #include <linux/in.h>