The BDAT analyzer should be supporting uint64_t sized chunks reasonably well,
but the ContentLine analyzer does not, And also, I totally got types for
RemainingChunkSize() and in DeliverStream() wrong, resulting in overflows
and segfaults when very large chunk sizes were used.
Tickled by OSS-Fuzz. Actually running the fuzzer locally only took a
few minutes to find the crash, too. Embarrassing.
