chromecast: Hide some private variable from settings

modules/stream_out/chromecast/cast.cpp

@@ -141,12 +141,15 @@ vlc_module_begin ()
     set_callbacks(Open, Close)
 
     add_string(SOUT_CFG_PREFIX "ip", NULL, IP_ADDR_TEXT, IP_ADDR_LONGTEXT, false)
+        change_private()
     add_integer(SOUT_CFG_PREFIX "port", CHROMECAST_CONTROL_PORT, PORT_TEXT, PORT_LONGTEXT, false)
+        change_private()
     add_integer(SOUT_CFG_PREFIX "http-port", HTTP_PORT, HTTP_PORT_TEXT, HTTP_PORT_LONGTEXT, false)
     add_bool(SOUT_CFG_PREFIX "video", true, HAS_VIDEO_TEXT, HAS_VIDEO_LONGTEXT, false)
     add_string(SOUT_CFG_PREFIX "mux", DEFAULT_MUXER, MUX_TEXT, MUX_LONGTEXT, false)
     add_string(SOUT_CFG_PREFIX "mime", "video/x-matroska", MIME_TEXT, MIME_LONGTEXT, false)
     add_integer(SOUT_CFG_PREFIX "show-perf-warning", 1, PERF_TEXT, PERF_LONGTEXT, true )
+        change_private()
     add_bool(SOUT_CFG_PREFIX "audio-passthrough", true, AUDIO_PASSTHROUGH_TEXT, AUDIO_PASSTHROUGH_LONGTEXT, false )
     add_bool(SOUT_CFG_PREFIX "multichannel-pcm", true, MULTICHANNEL_PCM_TEXT, MULTICHANNEL_PCM_LONGTEXT, false );