sd.conf tunable enhancements
It would be useful if un_victim_retry_count could be set from a tunable like the others, rather than being fixed at twice the default (not tunable-defined) timeout retry count of 3 or 5. This would make it easier to avoid pointless repetitive retries.
In addition, it would be helpful if zero-length vid/pid entries matched every device. Currently they would if passed to sd_sdconf_id_match(), but the two places that actually check this treat a zero-length vid/pid as match-never instead of match-always. Since a match-never entry has no possible utility, a different interpretation should be used.