made error messages debug4 messages (since they aren't really errors)

src/plugins/accounting_storage/common/common_as.c

@@ -827,10 +827,10 @@ extern int archive_write_file(Buf buffer, char *cluster_name,
 	else {			/* file shuffle */
 		(void) unlink(old_file);
 		if (link(reg_file, old_file))
-			error("Link(%s, %s): %m", reg_file, old_file);
+			debug4("Link(%s, %s): %m", reg_file, old_file);
 		(void) unlink(reg_file);
 		if (link(new_file, reg_file))
-			error("Link(%s, %s): %m", new_file, reg_file);
+			debug4("Link(%s, %s): %m", new_file, reg_file);
 		(void) unlink(new_file);
 	}
 	xfree(old_file);