package/janus-gateway: add an option to remove the HTML demos

janus-gateway comes with an example website to test its features.
Since the bump to 0.10.3, this website takes 1.8MiB uncompressed on
the target, among which is a 1MiB video sample which does not compress
well.

Signed-off-by: Nicolas Cavallari <nicolas.cavallari@green-communications.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/janus-gateway/Config.in

@@ -18,6 +18,12 @@ menuconfig BR2_PACKAGE_JANUS_GATEWAY
 
 if BR2_PACKAGE_JANUS_GATEWAY
 
+config BR2_PACKAGE_JANUS_GATEWAY_DEMOS
+	bool "HTML demos"
+	help
+	  Install the demonstration website, as featured on
+	  https://janus.conf.meetecho.com/
+
 comment "plugins"
 
 config BR2_PACKAGE_JANUS_GATEWAY_AUDIO_BRIDGE

package/janus-gateway/janus-gateway.mk

@@ -22,6 +22,13 @@ JANUS_GATEWAY_CONF_OPTS = \
 	--disable-data-channels \
 	--disable-sample-event-handler
 
+ifeq ($(BR2_PACKAGE_JANUS_GATEWAY_DEMOS),)
+define JANUS_GATEWAY_REMOVE_DEMOS
+	$(RM) -fr $(TARGET_DIR)/usr/share/janus/demos/
+endef
+JANUS_GATEWAY_POST_INSTALL_TARGET_HOOKS += JANUS_GATEWAY_REMOVE_DEMOS
+endif
+
 ifeq ($(BR2_PACKAGE_JANUS_GATEWAY_AUDIO_BRIDGE),y)
 JANUS_GATEWAY_DEPENDENCIES += opus
 JANUS_GATEWAY_CONF_OPTS += --enable-plugin-audiobridge