The `git_odb_stream` members `declared_size` and `received_bytes` are
both of the type `git_off_t`, which we usually defined to be a 64 bit
signed integer. Thus, passing these members to "PRIdZ" formatters is not
correct, as they are not guaranteed to accept big enough numbers.
Instead, use the "PRId64" formatter, which is able to represent 64 bit
signed integers.