fix not working when sending with netcat

[osiris-plus]

for some reason it times out when trying to read a line from socket connection

[osiris-plus]

https://github.com/osiris-plus/luadev-sh

[Cynosphere]

This fix did not change anything in my testing of using both gnu-netcat and openbsd-netcat in MinGW.

nmap's ncat works fine without needing this fix.

[osiris-plus]

This happens with nmap for windows.

[osiris-plus]

Idk why there's even a zero timeout, I guess luasocket is not async? Then the correct fix would be trying to read the socket next frame if there's a timeout error (vararg 2 of read)