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/android/fdsan.h b/libc/include/android/fdsan.h
index 4540498..fd0a63f 100644
--- a/libc/include/android/fdsan.h
+++ b/libc/include/android/fdsan.h
@@ -28,9 +28,10 @@
 
 #pragma once
 
+#include <sys/cdefs.h>
+
 #include <stdbool.h>
 #include <stdint.h>
-#include <sys/cdefs.h>
 
 __BEGIN_DECLS