Fix potential overlap dest buffer

Fix potential overlap dest buffer

To meet requirements of Common Criteria certification vulnerablility
assessment. Static code analysis has been run and found the following
error.  Overlapping_buffer: The source buffer potentially overlaps
with the destination buffer, which results in undefined
behavior for "memcpy".

The change is to use memmove instead of memcpy.

Signed-off-by: Nigel Croxon <ncroxon@redhat.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>