tmate: send Ctrl + c when openning a session

This skips the initial messages.
And let clients see the prompt when joining
instead of a black screen.

Author: germanferrero

packages/ubus-tmate/files/usr/lib/lua/tmate.lua

@@ -39,6 +39,7 @@ end
 
 function tmate.open_session()
   tmate.cmd_as_str("new-session -d")
+  tmate.cmd_as_str("send-keys C-c")
 end
 
 function tmate.wait_session_ready()