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/stdint.h b/libc/include/stdint.h
index 322a81c..772fe8b 100644
--- a/libc/include/stdint.h
+++ b/libc/include/stdint.h
@@ -29,9 +29,10 @@
 #ifndef _STDINT_H
 #define _STDINT_H
 
+#include <sys/cdefs.h>
+
 #include <bits/wchar_limits.h>
 #include <stddef.h>
-#include <sys/cdefs.h>
 
 typedef signed char __int8_t;
 typedef unsigned char __uint8_t;