kcptun-libev v2.1.2

Changes since v2.1.1:

1. [security] Invalid packets are now unable to keep the connection alive.
2. [generic] Fix several unexpected event routines. (reduces CPU usage)
3. [generic] Rebind sockets after ping timeout. (enables self-healing after network device restart)
4. [build] Fix crash in armv7 build.

Check README for more information.

If you downloaded a *-static build, you don't have to install runtime dependencies.