esxDomainLookupByUUID() and esxDomainIsActive() lookup a domain by asking
ESX for all known domains and searching manually for the one with the
matching UUID. This is inefficient. The VI API allows to lookup by UUID
directly: FindByUuid().

* src/esx/esx_driver.c: change esxDomainLookupByUUID() and esxDomainIsActive()
  to use esxVI_LookupVirtualMachineByUuid(), also reorder some functions to
  keep them in sync with the driver struct