* gst/qtdemux/qtdemux_fourcc.h: Add new fourccs for use by the mj2
  unpacker.
* gst/qtdemux/qtdemux.c (qtdemux_parse_trak): Unpack JPEG2000 component
  mapping and channel definitions from the jp2h header. Will add
  component-map and channel-definitions elements to the caps if the
  component maps or channel definitions are nonstandard, where standard
  order means RGB, 444 packed YUV, or greyscale, with no alpha channel.

Fixes #598915.