RegionStoreManager::getSizeInElements used 'int' for size
calculations, and ProgramState::assumeInBound fell back
to 'int' as well for its index calculations. This causes
truncation for sufficiently large sizes/indexes.
Use ArrayIndexTy (long long) in these instances to prevent overflow
problems.
As you correctly pointed, ssize_t is 32-bit on 32-bit systems. Therefore, it is too short. So, we can leave this line as-is.