Default to XEN44 instead of XEN41.

tbsetup/ns2ir/elabinelab-xen.ns

 #
-# Copyright (c) 2004-2014 University of Utah and the Flux Group.
+# Copyright (c) 2004-2014, 2016 University of Utah and the Flux Group.
 # 
 # {{{EMULAB-LICENSE
 # 
@@ -146,7 +146,7 @@ if { ${::GLOBALS::elabinelab_singlenet} == 0 } {
     }
 }
 
-set xenos XEN41-64-STD
+set xenos XEN44-64-STD
 if {[info exists ::TBCOMPAT::elabinelab_nodeos("xenhost")]} {
     namespace eval TBCOMPAT {
 	set xenos $elabinelab_nodeos("xenhost")