kcptun-libev v2.2.1

Changes since v2.2:

1. [security] Fixed an issue where server-side obfs sessions could be replaced by new connections from same address.
2. [obfs] Close related sessions when obfs connection is lost.
3. [obfs] Add scheduled redial after connection lost.
4. [performance] Overall performance tweaks. Reduce lags under high load.
5. [observability] Improve stats format, add stateless stats. Upgrade to HTTP/1.1.
6. [contrib] Sync upstream changes.
7. [log] Write to syslog when -d is specified.
8. [build] Support Android.

Build variants:

• -static: does not require any shared library at runtime.
• -android, -win32: requires only platform provided libraries.
• other: runtime dependencies should be installed.

Full Changelog: v2.2...v2.2.1