FlagTaskAsFinished now returns TRUE if all sub-tasks are terminated too,
instead of always returning 0.
Use a spinlock instead of a mutex to protect the scan task list.
RemoveChildTask now returns TRUE if the parent task and all its children are completed,
instead of returning an error that can not happen.

Set bool_termine_mere to TRUE (unitialized variable) in the case where RemoveChildTask was not called.
AddChildTask cannot fail.
InsertTask_to_Stack cannot fail.
Robinhood_StatsScan cannot fail, so remove the return value.

This trickles down to FSScan_DumpStats and FSScan_StoreStats which also
don't return a value anymore.
Robinhood_StopScanModule cannot fail, so do not return a value.

This trickles down to FSScan_Terminate.
FSScan_Wait cannot fail, so do not return a value.
Make BuildFidPath more efficient.
Scan a Lustre tree of any depth.

The scanning is now done from /mount_point/.lustre/fid/ instead of the regular Linux path.
Let rbh-find and rbh-du print any length pathnames.
Fix test 100.