Silently ignored flags get in the way of new features that
use those flags.

Regarding ESX migration flags - right now, ESX silently enforces
VIR_MIGRATE_PERSIST_DEST, VIR_MIGRATE_UNDEFINE_SOURCE, and
VIR_MIGRATE_LIVE, even if those flags were not supplied; it ignored
other flags.  This patch does not change the implied bits (it permits
but does not require them), but enforces only the supported bits.
If further cleanup is needed to be more particular about migration
flags, that should be a separate patch.

* src/esx/esx_device_monitor.c (esxDeviceOpen): Reject unknown
flags.
* src/esx/esx_driver.c (esxOpen, esxDomainReboot)
(esxDomainXMLFromNative, esxDomainXMLToNative)
(esxDomainMigratePrepare, esxDomainMigratePerform)
(esxDomainMigrateFinish): Likewise.
* src/esx/esx_interface_driver.c (esxInterfaceOpen): Likewise.
* src/esx/esx_network_driver.c (esxNetworkOpen): Likewise.
* src/esx/esx_nwfilter_driver.c (esxNWFilterOpen): Likewise.
* src/esx/esx_secret_driver.c (esxSecretOpen): Likewise.
* src/esx/esx_storage_driver.c (esxStorageOpen): Likewise.