Fix potentially undefined behaviour when computing a sha1 value.

libiberty/
	* sha1.c (sha1_process_bytes): Use memmove in place of memcpy.

libiberty/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;
     }