Crash: encode_NameValue_list called with count=21, s=NULL on worker
rejoin, causing SIGSEGV in persist_worker_hook_fun.
Root cause: free_name_val_list(xce_name_val_t***, int) accepted count by
value. It zeroed *vals (resvals_to_sched = NULL) but could not zero
nresvals_to_sched. Any caller that freed the scheduler resource snapshot
(opget.c workerlist, reply.c clusterconf, dataex.c, sched.c dispatch)
left nresvals_to_sched stale. When the worker later rejoined and the
WAL HOOK fired, the WAL encoder read count=21 with a NULL pointer.
Fix: change signature to free_name_val_list(xce_name_val_t***, int*)
so both fields are zeroed atomically. Update all 7 call sites.
- create_lost_and_found(): provide hostattrs_t so makeWorker succeeds
- collect_queues/collect_workers (dataex.c): skip lost_and_found sentinel
so it is never pushed to apiserver or scheduler
- mark_worker_unavail(): reset hosttype/hostmodel to "unknown" and zero
all numeric attrs, then update resvals and slots — prevents stale
capacity from being visible while the host is down
- restore_worker(): apply the same attr reset on WAL recovery so
restored-but-unavailable workers advertise no capacity until reconnect;
also remove dead calloc() that was immediately overwritten by makeWorker
- Extract reset_hostattrs_unknown() helper to eliminate copy-paste
- Define XCE_LOST_AND_FOUND_NAME constant in config_repl.h; replace all
six raw "lost_and_found" string literals across config_repl.c and dataex.c
