qemu: Check for user alias collisions in coldplug
qemu: Check for user alias collisions in coldplug

https://bugzilla.redhat.com/show_bug.cgi?id=1697676

If an user tries to attach a device with colliding user alias
then we attach it happily and thus leave domain unable to start.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

nertpinx/libvirt,jardasgit/libvirt,libvirt/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,libvirt/libvirt,jardasgit/libvirt,zippy2/libvirt,fabianfreyer/libvirt,zippy2/libvirt,nertpinx/libvirt,andreabolognani/libvirt,crobinso/libvirt,crobinso/libvirt,eskultety/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,nertpinx/libvirt,eskultety/libvirt,olafhering/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,nertpinx/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,olafhering/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,eskultety/libvirt,crobinso/libvirt,jardasgit/libvirt,andreabolognani/libvirt,nertpinx/libvirt,olafhering/libvirt,eskultety/libvirt,zippy2/libvirt,jardasgit/libvirt,crobinso/libvirt,libvirt/libvirt,eskultety/libvirt,jfehlig/libvirt