Support critical SAN extension
See reported issue on acme-tiny: https://github.com/diafygi/acme-tiny/issues/216
and the fix: https://github.com/diafygi/acme-tiny/pull/217/files
See reported issue on acme-tiny: https://github.com/diafygi/acme-tiny/issues/216
and the fix: https://github.com/diafygi/acme-tiny/pull/217/files