[1/n] ResourceTracker: avoid locking throughout encodes

Bug: 177241396

This is in preparation for sequence number based encode/decode.
The guest can't be holding the ResourceTracker lock while the host
is waiting for other commands in order to retire them in order.

Change-Id: Ief53bfdedb678b3bc43f5184dfb9b6481ea56e5b
1 file changed