mkvparser: Fix integer overflow in Block::GetTime

tc * scale could overflow theoretically (as it did in a fuzzed
file). The return -1 isn't really well defined, but that'll
probably do given this this is an extreme outlier case.

BUG=b/64953172

Change-Id: Id4aba673c3f85dee6ee25cc5f4b2db73b30ca8b3
1 file changed