Fix some formatting style.
TS-2708: refactor and modernize the tcp_info plugin

Always build the tcp_info plugin, even if it doesn't end up doing
anything useful on the build platform. This is convenient for
development.

Only sample and log TCP metrics after it passes the sample threshold
to reduce unnecessary work.

Add IPv6 support. Use TS*Assert instead of assert. Remove the Config
global variable. Add a txn_close hook.

Use the text logging API rather than writing custom logs.
TS-2714: promote the tcp_info plugin to stable as 'tcpinfo'
Revert typos in ts.h