Remove a comment which is now incorrect.

Before 5d305d86bd, this comment was
correct, but now it says we do something which we don't actually do.
Accordingly, remove the comment.

src/interfaces/libpq/libpq-int.h

@@ -364,7 +364,6 @@ struct pg_conn
 	PGnotify   *notifyTail;		/* newest unreported Notify msg */
 
 	/* Connection data */
-	/* See PQconnectPoll() for how we use 'int' and not 'pgsocket'. */
 	pgsocket	sock;			/* FD for socket, PGINVALID_SOCKET if
 								 * unconnected */
 	SockAddr	laddr;			/* Local address */