BUG/MEDIUM: ssl: disable kTLS on OpenSSL versions affected by a known bug

BUG/MEDIUM: ssl: disable kTLS on OpenSSL versions affected by a known bug

With vanilla OpenSSL, a blocked kTLS record keeps referencing the caller's
buffer and the library retries from it, even though
SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER is set; the H2 fast-forward reuses that
buffer, so streams get corrupted. Upstream fixed this in 3.4.6 and 3.5.7, so
disable kTLS on older versions and report it, with "tune.ssl.ktls-unsafe" to
opt in anyway.

To be backported to 3.3 and 3.4.