On preflight to compute output size, device name & unique ID were
counted only once per device.
Then, on copy, these two were copied on every MOUNTMGR_MOUNT_POINT
structure. This is counter efficient (data duplication) but also,
it was overruning the output buffer, since the preflight was not
expecting these extra copies.
We must query the target device, and not the symbolic link
we attempt to create. The later will always fail as it doesn't
exist yet.
This fixes MountMgrCreatePointWorker not working.
This fixes returning too small structure on an IOCTL_MOUNTMGR_QUERY_POINTS call.
The multiple MOUNTMGR_MOUNT_POINT structures were ignored and thus the data of the
first one were erased by the multiple structures.
MountMgr now returns consistent output on this IOCTL call.
