Move from memmove to memmove_s.

Change-Id: I791029d82c2ed6d3d9f23eada87730ae037c9b6c
diff --git a/inc/hf/std.h b/inc/hf/std.h
index f502346..101516e 100644
--- a/inc/hf/std.h
+++ b/inc/hf/std.h
@@ -31,3 +31,4 @@
  */
 void memset_s(void *dest, rsize_t destsz, int ch, rsize_t count);
 void memcpy_s(void *dest, rsize_t destsz, const void *src, rsize_t count);
+void memmove_s(void *dest, rsize_t destsz, const void *src, rsize_t count);