gst/elements/gstfdsrc.*: Port fd:// URI handler from 0.8 to fdsrc

gst/elements/gstfdsrc.*: Port fd:// URI handler from 0.8 to fdsrc

Original commit message from CVS:
* gst/elements/gstfdsrc.c: (_do_init), (gst_fdsrc_class_init),
(gst_fdsrc_init), (gst_fdsrc_dispose), (gst_fdsrc_set_property),
(gst_fdsrc_uri_get_type), (gst_fdsrc_uri_get_protocols),
(gst_fdsrc_uri_get_uri), (gst_fdsrc_uri_set_uri),
(gst_fdsrc_uri_handler_init):
* gst/elements/gstfdsrc.h:
Port fd:// URI handler from 0.8 to fdsrc