When enabled, no final TCP RST segment or SCTP ABORT chunk is sent
to cleanup the state at the SUT.

the main thread. But we are dying anyway.

not yet used.

It defines _GNU_SOURCE, which is needed on Linux for some
includes.

Includes https://github.com/google/packetdrill/commit/c5013aa73b973689a2af92f49e28f1695e905e60.

https://github.com/google/packetdrill/commit/77ab15806a56de226345fbe1910139829e431fe0

This fixes CID 337710

 setsockopt(3, SOL_SOCKET, SO_ACCEPTFILTER, {af_name = "dataready"}, ...) = 0

This fixes the memory handling of the linger, accept_filter, and
tcp_function_set socket options.