Add missing headers for compilation on x86 targets

Change-Id: I5f4dc797b353a0f01fa00d38375ec303bf863254
diff --git a/init/devices.c b/init/devices.c
index db229d3..036b8f7 100644
--- a/init/devices.c
+++ b/init/devices.c
@@ -15,6 +15,7 @@
  */
 
 #include <errno.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/stat.h>