REORG/MEDIUM: replace stream interface protocol functions by a proto pointer

The stream interface now makes use of the socket protocol pointer instead
of the direct functions.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index f709e73..478bff5 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -70,6 +70,7 @@
 	.sock_addrlen = sizeof(struct sockaddr_in),
 	.l3_addrlen = 32/8,
 	.accept = &stream_sock_accept,
+	.connect = tcp_connect_server,
 	.bind = tcp_bind_listener,
 	.bind_all = tcp_bind_listeners,
 	.unbind_all = unbind_all_listeners,
@@ -88,6 +89,7 @@
 	.sock_addrlen = sizeof(struct sockaddr_in6),
 	.l3_addrlen = 128/8,
 	.accept = &stream_sock_accept,
+	.connect = tcp_connect_server,
 	.bind = tcp_bind_listener,
 	.bind_all = tcp_bind_listeners,
 	.unbind_all = unbind_all_listeners,