Currently the build of libvirt_lxc will cause recompilation
of all sources under src/util, src/conf, src/security and
more. Switch the libvirt_lxc process to link against the
libtool convenience libraries that are already built as
part of the main libvirt.os & libvirtd build process
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>