omadec: Fix wrong number of array elements

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: David Goldwich <david.goldwich@gmail.com>
CC:libav-stable@libav.org
Signed-off-by: Anton Khirnov <anton@khirnov.net>
omadec: check GEOB sizes against buffer size

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: David Goldwich <david.goldwich@gmail.com>
CC:libav-stable@libav.org
Signed-off-by: Anton Khirnov <anton@khirnov.net>
omadec: loosen format probing constraints

Imporoves detection of some files in the wild:

- ID3v2 a.k.a. "ea3" header is optional.
- Version and flags in ID3v2 header are unspecified.

Signed-off-by: David Goldwich <david.goldwich@gmail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>