windowing/gbm: hide and disable setting Use Display As Clock

[HiassofT]

Description

Use display as clock is not supported on GBM and before the
multi-windowing change it has been hidden in settings via gbm.xml.

Hide it in settings so it can't be enabled in player settings and
also make sure it's disabled in case it had been enabled before,
otherwise users would be left without audio passthrough and no
option to fix this via the GUI.

Motivation and Context

Restore behaviour prior to the multi-windowing change and make sure
users aren't able to select a known non-working option

How Has This Been Tested?

Runtime tested on LibreELEC RPi4, checked that previously enabled setting
is getting disabled (with a WARN in log) and that option is not shown in video
player settings.

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[HiassofT]

updated with suggested changes

[lrusak]

@DaveTBlake it's your button 😄

[HeresJonny]

AFAIK, the speedup functionality https://forum.kodi.tv/showthread.php?tid=10023&pid=2379972#pid2379972 depends on "Sync playback to display". This is one of THE killer functions within Kodi for me to watch movies and TV episodes faster. Please be sure to provide an alternative to keep it working.

[lrusak]

AFAIK, the speedup functionality https://forum.kodi.tv/showthread.php?tid=10023&pid=2379972#pid2379972 depends on "Sync playback to display". This is one of THE killer functions within Kodi for me to watch movies and TV episodes faster. Please be sure to provide an alternative to keep it working.

Please don't spam old PR's. If you have a concern please bring it up in the forum thanks.

[HeresJonny]

Well, 2 days is certainly far from old, and you have taken note of it so my work is done. I don't want to waste your time by having you read this twice.