Make VNC support optional

Per default VNC is enabled.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/qerror.h b/qerror.h
index f732d45..df61d2c 100644
--- a/qerror.h
+++ b/qerror.h
@@ -171,4 +171,7 @@
 #define QERR_VNC_SERVER_FAILED \
     "{ 'class': 'VNCServerFailed', 'data': { 'target': %s } }"
 
+#define QERR_FEATURE_DISABLED \
+    "{ 'class': 'FeatureDisabled', 'data': { 'name': %s } }"
+
 #endif /* QERROR_H */