qemu: support emulator pinning

qemu: support emulator pinning

Introduce 2 APIs to support emulator threads pin in qemu driver.

    1) qemudDomainPinEmulator: setup emulator threads pin info.
    2) qemudDomainGetEmulatorPinInfo: get all emulator threads pin info.

They are similar to qemudDomainPinVcpuFlags and qemudDomainGetVcpuPinInfo.
And also, remoteDispatchDomainPinEmulatorFlags and remoteDispatchDomainGetEmulatorPinInfo
functions are introduced.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>