qemu: hostdev: Add checks if PCI passthrough is available in the host
qemu: hostdev: Add checks if PCI passthrough is available in the host

Add code to check availability of PCI passhthrough using VFIO and the
legacy KVM passthrough and use it when starting VMs and hotplugging
devices to live machine.

agx/libvirt,jardasgit/libvirt,libvirt/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,rlaager/libvirt,eskultety/libvirt,elmarco/libvirt,datto/libvirt,VenkatDatta/libvirt,agx/libvirt,zippy2/libvirt,elmarco/libvirt,datto/libvirt,agx/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,eskultety/libvirt,zhlcindy/libvirt-1.1.4-maintain,crobinso/libvirt,nertpinx/libvirt,crobinso/libvirt,cbosdo/libvirt,jardasgit/libvirt,datto/libvirt,jfehlig/libvirt,taget/libvirt,taget/libvirt,rlaager/libvirt,cbosdo/libvirt,cbosdo/libvirt,eskultety/libvirt,agx/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,elmarco/libvirt,olafhering/libvirt,elmarco/libvirt,agx/libvirt,datto/libvirt,zhlcindy/libvirt-1.1.4-maintain,VenkatDatta/libvirt,eskultety/libvirt,andreabolognani/libvirt,libvirt/libvirt,olafhering/libvirt,fabianfreyer/libvirt,eskultety/libvirt,shugaoye/libvirt,VenkatDatta/libvirt,zhlcindy/libvirt-1.1.4-maintain,nertpinx/libvirt,andreabolognani/libvirt,taget/libvirt,taget/libvirt,shugaoye/libvirt,shugaoye/libvirt,nertpinx/libvirt,zhlcindy/libvirt-1.1.4-maintain,cbosdo/libvirt,VenkatDatta/libvirt,olafhering/libvirt,zippy2/libvirt,andreabolognani/libvirt,rlaager/libvirt,jfehlig/libvirt,jfehlig/libvirt,jfehlig/libvirt,libvirt/libvirt,rlaager/libvirt,zippy2/libvirt,cbosdo/libvirt,taget/libvirt,jardasgit/libvirt,nertpinx/libvirt,andreabolognani/libvirt,elmarco/libvirt,zhlcindy/libvirt-1.1.4-maintain,nertpinx/libvirt,rlaager/libvirt,crobinso/libvirt,libvirt/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,datto/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jardasgit/libvirt,zippy2/libvirt,crobinso/libvirt