[mod_wstunnel] remove invalid appended '\0'
[mod_wstunnel] remove invalid appended '\0'

remove invalid appended '\0' in code originating from Norio Kobota
mod_websocket_frame.c.  /* needs '\0' char to send */ is not valid

x-ref:
  "wstunnel sample config"
  https://redmine.lighttpd.net/boards/2/topics/7600

lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4