BUG/MEDIUM: ssl: fix generate-certificates option when SNI greater than 64bytes

BUG/MEDIUM: ssl: fix generate-certificates option when SNI greater than 64bytes

The problem is that the certificate is generated with a CN greater than
64 bytes when the SNI is too long, which is not suppose to be supported,
and will end up with a handshake failure.

The patch fixes the issue by avoiding to add a CN when the SNI is longer than
64 bytes. Indeed this is not a mandatory field anymore and was deprecated more
than 20 years ago. The SAN DNS is enough for this case.

Must be backported in every stable branches.