Signed-off-by: Zhou Peng <zhoupeng@xxxxxxxxxxxxxxx>

tools/libxl/libxl__build_device_model_args_new/old: The condition is so strong that user has no chance to disable the vnc,
especially considering what has been done in parse_config_data(),which is not resonable with vnc option in vm-cfg file.
If user explicitly set "vnc=0", vnc should be disabled. User should have the chance to only use sdl, other remote display(spice) even nothing.

diff -r 41879bb8d174 -r 6871474a2a09 tools/libxl/libxl_dm.c
--- a/tools/libxl/libxl_dm.c	Fri Apr 15 09:51:14 2011 +0800
+++ b/tools/libxl/libxl_dm.c	Fri Apr 15 10:06:59 2011 +0800
@@ -55,7 +55,7 @@ static char ** libxl__build_device_model
     if (info->dom_name)
         flexarray_vappend(dm_args, "-domain-name", info->dom_name, NULL);
 
-    if (info->vnc || info->vncdisplay || info->vnclisten || info->vncunused) {
+    if (info->vnc) {
         char *vncarg;
         if (info->vncdisplay) {
             if (info->vnclisten && strchr(info->vnclisten, ':') == NULL) {
@@ -205,7 +205,7 @@ static char ** libxl__build_device_model
     if (info->dom_name) {
         flexarray_vappend(dm_args, "-name", info->dom_name, NULL);
     }
-    if (info->vnc || info->vncdisplay || info->vnclisten || info->vncunused) {
+    if (info->vnc) {
         int display = 0;
         const char *listen = "127.0.0.1";