[MPlayer-dev-eng] another RGB ordering fix for altivec

[Alan Curry]

Ivan Kalvachev writes the following:
>
>Could there be argb64 ?? (e.g. film gimp / cine paint)

At an unspecified future time, it could appear. Then we'd either
s/IMGFMT_ARGB/IMGFMT_ARGB32/ throughout mplayer or decide to keep it as it
is, with the 32 implied. Either way, why should that stop us from using
consistent names for 32-bit formats now?