Merge several equal serialization indexes.

(cherry picked from commit 4c01b6782d9c0f5a9de76aab720a6c356c55766c)
Add support for VMWare dialect of EXTENDED COPY command, aka VAAI Clone.

This allows to clone VMs and move them between LUNs inside one storage
host without generating extra network traffic to the initiator and back,
and without being limited by network bandwidth.

LUNs participating in copy operation should have UNIQUE NAA or EUI IDs set.
For LUNs without these IDs VMWare will use traditional copy operations.

Beware: the above LUN IDs explicitly set to values non-unique from the VM
cluster point of view may cause data corruption if wrong LUN is addressed!

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.

(cherry picked from commit 7b21dd3b31b8f07a5be046ff2f243eb5fd4b1e21)