gst/tcp/: Removed fdset and stress test, they are now known as GstPoll in core.

gst/tcp/: Removed fdset and stress test, they are now known as GstPoll in core.

Original commit message from CVS:
Patch by: Peter Kjellerstedt  <pkj at axis com>
* gst/tcp/Makefile.am:
* gst/tcp/fdsetstress.c:
* gst/tcp/gstfdset.c:
* gst/tcp/gstfdset.h:
Removed fdset and stress test, they are now known as GstPoll in
core.
* gst/tcp/gstmultifdsink.c: (gst_multi_fd_sink_class_init),
(gst_multi_fd_sink_add_full), (gst_multi_fd_sink_remove),
(gst_multi_fd_sink_clear), (gst_multi_fd_sink_remove_client_link),
(gst_multi_fd_sink_handle_client_write),
(gst_multi_fd_sink_queue_buffer),
(gst_multi_fd_sink_handle_clients), (gst_multi_fd_sink_start),
(gst_multi_fd_sink_stop):
* gst/tcp/gstmultifdsink.h:
* gst/tcp/gsttcp.c: (gst_tcp_socket_read), (gst_tcp_socket_close),
(gst_tcp_read_buffer), (gst_tcp_gdp_read_buffer),
(gst_tcp_gdp_read_caps):
* gst/tcp/gsttcp.h:
* gst/tcp/gsttcpclientsink.c: (gst_tcp_client_sink_init),
(gst_tcp_client_sink_setcaps), (gst_tcp_client_sink_render),
(gst_tcp_client_sink_start), (gst_tcp_client_sink_stop):
* gst/tcp/gsttcpclientsink.h:
* gst/tcp/gsttcpclientsrc.c: (gst_tcp_client_src_init),
(gst_tcp_client_src_create), (gst_tcp_client_src_start),
(gst_tcp_client_src_stop), (gst_tcp_client_src_unlock):
* gst/tcp/gsttcpclientsrc.h:
* gst/tcp/gsttcpserversink.c: (gst_tcp_server_sink_handle_wait),
(gst_tcp_server_sink_init_send), (gst_tcp_server_sink_close):
* gst/tcp/gsttcpserversink.h:
* gst/tcp/gsttcpserversrc.c: (gst_tcp_server_src_init),
(gst_tcp_server_src_create), (gst_tcp_server_src_start),
(gst_tcp_server_src_stop), (gst_tcp_server_src_unlock):
* gst/tcp/gsttcpserversrc.h:
Port to GstPoll. See #505417.