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/sys/param.h b/libc/include/sys/param.h
index 1c991ae..99b6a07 100644
--- a/libc/include/sys/param.h
+++ b/libc/include/sys/param.h
@@ -33,10 +33,11 @@
  * @brief Various macros.
  */
 
+#include <sys/cdefs.h>
+
 #include <endian.h>
 #include <limits.h>
 #include <linux/param.h>
-#include <sys/cdefs.h>
 
 /** The unit of `st_blocks` in `struct stat`. */
 #define DEV_BSIZE 512