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>

sha1.c

@@ -258,7 +258,7 @@ sha1_process_bytes (const void *buffer, size_t len, struct sha1_ctx *ctx)
 	{
 	  sha1_process_block (ctx->buffer, 64, ctx);
 	  left_over -= 64;
-	  memcpy (ctx->buffer, &ctx->buffer[16], left_over);
+	  memmove (ctx->buffer, &ctx->buffer[16], left_over);
 	}
       ctx->buflen = left_over;
     }