MEDIUM: ssl: add support for smaller SSL records

MEDIUM: ssl: add support for smaller SSL records

There's a very common openssl patch on the net meant to significantly
reduce openssl's memory usage. This patch has been provided for many
versions now, and it makes sense to add support for it given that it
is very simple. It only requires to add an extra SSL_MODE flag. Just
like for other flags, if the flag is unknown, it's unset. About 44kB
of memory may be saved per SSL session with the patch.