this is the patch to add support for multiple serial ports to the
libvirt Xen driver. It support both old style (serial = "pty") and
new style (serial = [ "/dev/ttyS0", "/dev/ttyS1" ]) definition and
tests for xml2sexpr, sexpr2xml and xmconfig have been added as well.

Written and tested on RHEL-5 Xen dom0 and working as designed but
the Xen version have to have patch for RHBZ #614004 but this patch
is for upstream version of libvirt.

Also, this patch is addressing issue described in RHBZ #670789.
Signed-off-by: NMichal Novotny <minovotn@redhat.com>