Ringbuf decoding failures on a recent image

[mkeeter]

On master (df09cf8), Humility can't decode ringbufs from a recent dump:

➜  ~ humility -d hubris.core.gimlet_seq.12 ringbuf
humility: attached to dump
humility: ring buffer drv_gimlet_seq_server::__RINGBUF in gimlet_seq:
humility: ringbuf dump failed: member missing from struct: cell
humility: ring buffer drv_gimlet_seq_server::vcore::__RINGBUF in gimlet_seq:
humility: ringbuf dump failed: not a u32: Base(U16(0))
humility: ring buffer drv_oxide_vpd::__RINGBUF in gimlet_seq:
humility: ringbuf dump failed: not a u32: Base(U16(0))
humility: ring buffer drv_packrat_vpd_loader::__RINGBUF in gimlet_seq:
humility: ringbuf dump failed: not a u32: Base(U16(0))

Here's the dump:
hubris.core.gimlet_seq.16.zip

[hawkw]

oh, shoot, that's my fault; oxidecomputer/hubris#1733 changed the ringbuf entry count from u32 to u16. we should probably change it back (or make humility happy with both, which is probably the Right Thing regardless)...