capabilities, cpu: use new array API

capabilities, cpu: use new array API

* src/conf/capabilities.h (_virCaps, _virCapsHost, _virCapsGuest)
(_virCapsGuestArch): Add additional fields.
* src/conf/cpu_conf.h (_virCPUDef): Likewise.
* src/conf/capabilities.c (virCapabilitiesFormatXML): Reflect
updated type.
(virCapabilitiesAddGuest, virCapabilitiesAddHostFeature)
(virCapabilitiesAddHostMigrateTransport)
(virCapabilitiesAddHostNUMACell, virCapabilitiesAddGuestFeature)
(virCapabilitiesAddGuestDomain): Use new array APIs.
* src/conf/cpu_conf.c (virCPUDefAddFeature, virCPUDefCopy)
(virCPUDefParseXML): Likewise.
* tests/testutilsqemu.c (testQemuCapsInit): Adjust test.