A pretty nasty deadlock occurs while trying to rename a VM in parallel
with virDomainObjListNumOfDomains.
The short description of the problem is as follows:

Thread #1:

qemuDomainRename:
    ------> aquires domain lock by qemuDomObjFromDomain
       ---------> waits for domain list lock in any of the listed functions:
          - virDomainObjListFindByName
          - virDomainObjListRenameAddNew
          - virDomainObjListRenameRemove

Thread #2:

virDomainObjListNumOfDomains:
    ------> aquires domain list lock
       ---------> waits for domain lock in virDomainObjListCount

Introduce generic virDomainObjListRename function for renaming domains.
It aquires list lock in right order to avoid deadlock. Callback is used
to make driver specific domain updates.
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>