package/libvncserver: disable gtk example

gtkvncviewer has been added since version 0.9.13 and
https://github.com/LibVNC/libvncserver/commit/2650cfc17bb7718e42bfff8510c15f011eda1b1f,
disable it as it is only an example

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit c89f62cec69a29b9f7441893b39d24e141fbe988)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libvncserver/libvncserver.mk

@@ -16,6 +16,7 @@ LIBVNCSERVER_CONF_OPTS = -DWITH_LZO=ON
 # only used for examples
 LIBVNCSERVER_CONF_OPTS += \
 	-DWITH_FFMPEG=OFF \
+	-DWITH_GTK=OFF \
 	-DWITH_SDL=OFF
 
 ifneq ($(BR2_TOOLCHAIN_HAS_THREADS),y)