Should set "number of frames" to bytes 24-27 of IVF header, not
duration.
It is described by [1], and confirmed by parsing all IVF files in [2].

This commit also updates the md5sum of refs to pass fate-cbs.

[1] Duck IVF - MultimediaWiki
https://wiki.multimedia.cx/index.php/Duck_IVF

[2] webm/vp8-test-vectors
https://chromium.googlesource.com/webm/vp8-test-vectorsSigned-off-by: Jianhui Dai <jianhui.j.dai@intel.com>
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>