[libvirt] libxl fixes/improvements for libvirt

Here several changes which improve the handling of Xen for me: * 0001-libxl-Use-id-from-virDomainObj-inside-the-driver.patch This is a re-send as I initially submitted that as a reply to some discussion. Starting from the visibly broken libxlDomainGetInfo when creating or rebooting a guest with virt-manager, I replaced all usage of dom->id with the more stable vm->def->id. * 0002-libxl-Set-disk-format-for-empty-cdrom-device.patch Fixes start of a guest after ejecting the iso image from a virtual CDROM drive (again using virt-manager). * 0003-libxl-Implement-basic-video-device-selection.patch Should fix the occasional disagreement about the used VNC port and adds the ability to select the standard VGA graphics from Xen. VRAM size seemed to work with that. Only for Cirrus, while the qemu command-line looks good, ones seems to end up with 32M. Note to people on the Xen list: I wonder whether libxenlight internally should somehow should fix up the situation where a caller sets up the video devices in the vfbs list but does not sync that with the information in the build info. Question probably is what the semantics should be. -Stefan