Add missing <malloc.h> and <string.h> includes.

Change-Id: Ia41756e607663d056e7d2fdd7ecbec7e5841a913
diff --git a/toolbox/restorecon.c b/toolbox/restorecon.c
index 3568625..cb5799e 100644
--- a/toolbox/restorecon.c
+++ b/toolbox/restorecon.c
@@ -1,6 +1,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #include <selinux/selinux.h>
 #include <selinux/android.h>