examples: Fix connection error handling 2

Fix two more cases in examples as
libvirt.open*() does not return None but raises an exception

Fixes: 283e2bc693
Signed-off-by: Philipp Hahn <hahn@univention.de>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

examples/domipaddrs.py

@@ -21,8 +21,9 @@ else:
     usage()
     sys.exit(2)
 
-conn = libvirt.open(uri)
-if conn == None:
+try:
+    conn = libvirt.open(uri)
+except libvirt.libvirtError:
     print "Unable to open connection to libvirt"
     sys.exit(1)