matroska_reset_status (a function that is used during seeking (among
other things)) used an int for the return value of avio_seek which
returns an int64_t. Checking the return value then indicated an error
even though the seek was successfull for targets in the range of
2GB-4GB, 6GB-8GB, ... This error implied that the status hasn't been
reset and in particular, the old level was still considered to be in
force, so that ebml_parse returned errors because the newly parsed
elements were of course not contained in the previously active and still
wrongly considered active master element any more.

Addresses ticket #8084.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>