MEDIUM: connection: remove conn_{data,sock}_poll_{recv,send}

We simply remove these functions and replace their calls with the
appropriate ones :

  - if we're in the data phase, we can simply report wait on the FD
  - if we're in the socket phase, we may also have to signal the
    desire to read/write on the socket because it might not be
    active yet.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 4460bb4..cb10661 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -657,7 +657,7 @@
 	if (connect(fd, (struct sockaddr *)&conn->addr.to, get_addr_len(&conn->addr.to)) < 0) {
 		if (errno == EALREADY || errno == EINPROGRESS) {
 			__conn_sock_stop_recv(conn);
-			__conn_sock_poll_send(conn);
+			fd_cant_send(fd);
 			return 0;
 		}