qtdemux: add support for 'vc-1' mapping as found in some ismv files

e.g. To_The_Limit_720_2962.ismv
qtdemux: add support for 'wma ' mapping as found in some ismv files

e.g. To_The_Limit_720_2962.ismv
qtdemux: improve debug logging of fourccs

If we can't show ASCII, at least show them
in big endian order.