Up until e7ddafd5 the Matroska muxer
wrote a secondary seek head referencing all the clusters. When this
was changed, a (now completely wrong) comment remained and the unique
remaining seek head was still called main_seekhead. This has been
changed.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>