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>
diff --git a/init/keychords.c b/init/keychords.c
index 53ab391..892cbdf 100644
--- a/init/keychords.c
+++ b/init/keychords.c
@@ -17,9 +17,11 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <linux/keychord.h>
+#include <unistd.h>
 
 #include "init.h"
 #include "log.h"
diff --git a/init/list.h b/init/list.h
index 0a7b28c..7b9ef32 100644
--- a/init/list.h
+++ b/init/list.h
@@ -17,6 +17,8 @@
 #ifndef _INIT_LIST_H_
 #define _INIT_LIST_H_
 
+#include <stddef.h>
+
 struct listnode
 {
     struct listnode *next;