Function SocketPair (Domain,SocketType,Protocol:Longint;var Pair:TSockArray) : Longint;
SocketPair creates 2 sockets in domain Domain, from type SocketType and using protocol Protocol.
The pair is returned in Pair, and they are indistinguishable.
The function returns -1 upon error and 0 upon success.
Errors are reported in SocketError, and are the same as in Socket