smartcard: turn on qemu support

smartcard: turn on qemu support

* src/qemu/qemu_command.c (qemuBuildCommandLine): Emit smartcard
options.
(qemuAssignDeviceAliases): Assign an alias for smartcards.
(qemuBuildControllerDevStr): Manage the usb-ccid controller.
* tests/qemuxml2argvtest.c (mymain): Add new tests.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-host.args: New
file.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-host-certificates.args:
Likewise.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-passthrough.args:
Likewise.
* tests/qemuxml2argvdata/qemuxml2argv-smartcard-controller.args:
Likewise.