[MPlayer-dev-eng] fixing rawi420 tv capture

[D Richard Felker III]

Apparently some silly Intel win32 codec has the I420 fourcc, which
conflicts with outfmt=i420 tv capture. This should be resolved by
either removing I420 from the fourcc's for i263 (is it really used?)
or else patching the tv stuff to use "i420" (lowercase) so it doesn't
conflict. However I couldn't find where in the source the tv stuff
sets the fourcc...

Rich