Configurable video delay to avoid a/v sync issue if bluetooth headset is used

When bluetooth headset is used, audio has some delay (~34-300 ms depending on codec/bluetooth version/etc) so movie watching is not comfortable due to lip sync issue.

Some vendors (e.g. LG (webos TV)) has special feature to avoid this issue. It is possible to configure video delay on their TVs to manage lip sync issue when bluetooth audio output is used.

It will be very cool if VLC has such settings (especially for mobile version).