Add select handler - still need read and free.

libguac/src/socket.c

@@ -194,6 +194,7 @@ guac_socket* guac_socket_open(int fd) {
 
     /* FIXME: Set read/write/free handlers */
     socket->write_handler  = __guac_socket_fd_write_handler;
+    socket->select_handler = __guac_socket_fd_select_handler;
 
     return socket;