smartcard: add domain conf support

smartcard: add domain conf support

* src/conf/domain_conf.h (virDomainSmartcardType): New enum.
(virDomainSmartcardDef, virDomainDeviceCcidAddress): New structs.
(virDomainDef): Include smartcards.
(virDomainSmartcardDefIterator): New typedef.
(virDomainSmartcardDefFree, virDomainSmartcardDefForeach): New
prototypes.
(virDomainControllerType, virDomainDeviceAddressType): Add ccid
enum values.
(virDomainDeviceInfo): Add ccid address type.
* src/conf/domain_conf.c (virDomainSmartcard): Convert between
enum and string.
(virDomainSmartcardDefParseXML, virDomainSmartcardDefFormat)
(virDomainSmartcardDefFree, virDomainDeviceCcidAddressParseXML)
(virDomainDefMaybeAddSmartcardController): New functions.
(virDomainDefParseXML): Parse the new XML.
(virDomainDefFormat): Convert back to XML.
(virDomainDefFree): Clean up.
(virDomainDeviceInfoIterate): Iterate over passthrough aliases.
(virDomainController, virDomainDeviceAddress)
(virDomainDeviceInfoParseXML, virDomainDeviceInfoFormat)
(virDomainDefAddImplicitControllers): Support new values.
* src/libvirt_private.syms (domain_conf.h): New exports.
* cfg.mk (useless_free_options): List new function.