gst/tcp/gstmultifdsink.*: Implement stubbed out properties unit-type, units-soft-max, units-max, to allow specifying ...

Original commit message from CVS:
* gst/tcp/gstmultifdsink.c: (gst_sync_method_get_type),
(gst_multi_fd_sink_class_init), (get_buffers_max), (find_limits),
(gst_multi_fd_sink_recover_client),
(gst_multi_fd_sink_queue_buffer), (gst_multi_fd_sink_set_property),
(gst_multi_fd_sink_get_property):
* gst/tcp/gstmultifdsink.h:
Implement stubbed out properties unit-type, units-soft-max,
units-max, to allow specifying maximum sizes in units other than
buffers.
Fixes #355935