Add missing deps on libxml2-devel & libtool. Don't introspect on RHEL6
Add missing deps on libxml2-devel & libtool. Don't introspect on RHEL6

JGulic/libvirt-glib,libvirt/libvirt-glib,JGulic/libvirt-glib,libvirt/libvirt-glib,libvirt/libvirt-glib,JGulic/libvirt-glib,JGulic/libvirt-glib,JGulic/libvirt-glib