Subtitle track selection not disabled even when there is no subtitle track
Tested on:
- windows 10
- linux debian stretch With vlc 3.0 master (20180206) and https://nightlies.videolan.org/build/win64/vlc-3.0.0-rc9-20180206-0505/
This happens only if you have previously played a media with a subtitle track.
Test protocol:
- add a file with a subtitle track to your playlist
- add a file with NO subtitle track to your playlist
- play the first file (with sub)
- play the next file (without sub)
- Go to "Subtitle->Sub track" menu: the item is enabled, but list is empty (it should be disabled)