gst/tcp/gstmultifdsink.c: Make sure we don't try to read more from a client that what ioctl says us or we deadlock.

Original commit message from CVS:
* gst/tcp/gstmultifdsink.c: (gst_multifdsink_class_init),
(gst_multifdsink_add), (gst_multifdsink_get_stats),
(gst_multifdsink_client_remove),
(gst_multifdsink_handle_client_read),
(gst_multifdsink_handle_client_write),
(gst_multifdsink_queue_buffer), (gst_multifdsink_handle_clients):
Make sure we don't try to read more from a client that what
ioctl says us or we deadlock.