Port recent changes from tcnative

There have been a few fixes/improvements lately in netty-tcnative. We should port those over to our engine.

A few that immediately stick out:

https://github.com/netty/netty-tcnative/pull/205
(and related https://github.com/netty/netty/pull/6123)

https://github.com/netty/netty-tcnative/pull/207
https://github.com/netty/netty-tcnative/pull/210

https://github.com/netty/netty-tcnative/pull/216
(and related https://github.com/netty/netty/pull/6201)

https://github.com/netty/netty/pull/6118
https://github.com/netty/netty/pull/6113
https://github.com/netty/netty/pull/6090
https://github.com/netty/netty/pull/6089
https://github.com/netty/netty/pull/6439

SSLEngine benchmarks:
https://github.com/netty/netty/pull/6360