configure: Drop vnc-ws feature from help text

Commit 8e9b0d2 (ui: convert VNC websockets to use crypto APIs) dropped
the --enable-vnc-ws option but forgot to update the help text. Fix this.

Cc: Daniel P. Berrange <berrange@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1437749257-3313-1-git-send-email-afaerber@suse.de
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/configure b/configure
index 704b34c..cd219d8 100755
--- a/configure
+++ b/configure
@@ -1337,7 +1337,6 @@
   vnc-sasl        SASL encryption for VNC server
   vnc-jpeg        JPEG lossy compression for VNC server
   vnc-png         PNG compression for VNC server
-  vnc-ws          Websockets support for VNC server
   cocoa           Cocoa UI (Mac OS X only)
   virtfs          VirtFS
   xen             xen backend driver support