Original commit message from CVS:
* gst/mxf/Makefile.am:
* gst/mxf/mxf.c: (plugin_init):
* gst/mxf/mxfvc3.c: (mxf_is_vc3_essence_track),
(mxf_vc3_handle_essence_element), (mxf_vc3_create_caps),
(mxf_vc3_init):
* gst/mxf/mxfvc3.h:
Add support for VC-3 (aka DNxHD essence, see SMPTE 2019-4).
This is untested because of lack of sample files but should
work fine.
