05d02f3c70
S3: the packs are read ahead, eight ranges at a time, straight into files in the spool. SMB: ranges are read in 8 MiB reads through libsmbclient instead of icewind's 1 MiB reads; over a line with a 130 ms round trip, reading was four times faster in a test (18 instead of 4.5 MiB/s).