Output is not updated as gamma resets when gamma control client disconnects

[kennylevinsen]

When a gamma-control client terminates or otherwise stops adjusting the gamma LUTs, the gamma is reset to the default values. However, this does not seem to lead to a proper output commit, and as a result the gamma is not reset before something else triggers a commit.

To observe this, it is important that nothing is submitting buffers on the monitor, and that the attempt itself does not lead to any submits.

1. Using multiple monitors: Leave one monitor empty, and on the other run your terminal, start gamma-control -b 10, and ctrl-c. The other monitor will not reset before you move your cursor to it.
2. Using ssh: Run an empty sway instance, and over ssh run gamma-control -b 10 and ctrl-c. The monitor should not update before you move the cursor.
3. On a single monitor without anything: ./gamma-control -b 10 & sleep 5; killall gamma-control; sleep 5. The last sleep is to delay prints in the terminal, which will lead to buffers being submitted. What you should see is 5 seconds before gamma resets, but you end up waiting the full 10 until the terminal prints something.

[emersion]

Can you try #2633?

[kennylevinsen]

That PR does the trick