- Make it possible to build the library and unit tests without
libevent.
- Build all command-line utilities in bin/
- Add perf_client and perf_server command-line utilities to test
performance according to the "perf" protocol.
- [API] New knob to set outgoing packet batch size.
- Aborted connection now become tickable immediately.
- Abort connection when HTTP/3 frame cannot be opened (can only happen
when malloc fails).