Not just in blob.SizedRef, but in blobserver.Fetch and
blobserver.FetchStreaming, too.
Blobs have a max size of 10-32 MB anyway, and the index.Corpus is now using
uint32 to save memory.
Change-Id: I1172445c2f9463fdaee55bfe0f1218d44be4aa53
make havecache/statcache named on disk by remote server's generation,
hide debug options in camput unless CAMLI_DEBUG=1 is set,
push havecache down into pkg/client.
Change-Id: Ic152397abc11b4ff3931468ffe93cf1eba62b438