Ignore errno returned from rewind() in the interface iterator

The clang-scan 19 has reported that we are ignoring errno after the call
to rewind().  As we don't really care about the result, just silence the
error, the whole code will be removed in the development version anyway
as it is not needed.

(cherry picked from commit dda5ba53df)

lib/isc/interfaceiter.c

@@ -366,6 +366,7 @@ static void
 linux_if_inet6_first(isc_interfaceiter_t *iter) {
 	if (iter->proc != NULL) {
 		rewind(iter->proc);
+		errno = 0; /* Ignore the errno */
 		(void)linux_if_inet6_next(iter);
 	} else {
 		iter->valid = ISC_R_NOMORE;