Incorrect Socket Flag for Non-Blocking Sockets

[osborners]

SOCK_IO_NONBLOCK is not a socket flag option for socket(), as used here in loopback.c:

io6Library/Application/loopback/loopback.c

Line 141 in a52bd52

tmp = socket(sn, Sn_MR_TCP4, port, SOCK_IO_NONBLOCK);

It should be SF_IO_NONBLOCK.

However, the change introduced here means that only SOCK_IO_NONBLOCK will set the socket mode to non-blocking: c9c9ef8#diff-5779d7831ac938e3f7d8cb0c0890060576acc6536afff3c010e7838367c7d9b3R172

21/05/24: A side effect of using SOCK_IO_NONBLOCK (=1) is that 'Force ARP' mode in Sn_MR2 gets enabled: https://github.com/Wiznet/io6Library/blob/master/Ethernet/socket.c#L163