Avoid occasional 'busy wait' for next render time in main loop.

[anvilvapre]

See #18491.

Fix for bug where:

• if now >= nextLogic && renderBeforeNextTick && Renderer.WindowIsSuspended
• then renderBeforeNextTick will never become false
• resulting the main loop to end up in a "busy wait"/"spin loop" to wait until now > nextRender
• causing 60+ execution per millisecond - until nextRender is reached

Changes:

• If window is suspended: Call Thread.sleep rather than busy wait/spin.
• Else: also ensure that renderBeforeNextTick will be false - even if there was not time to render - and we skip.

In the rare occasion where !haveSomeTimeUntilNextLogic && !forceRender a render is skipped. This seemed to be the original implied intended behavior. May cause issues if certain logic relies on render ticks to occur. But this also already happens/happened in suspended window mode.

I myself would prefer to update next render time also based on actual time spent rendering. But i guess then you would not be able to meet the indended fps. It would be beneficial on slower systems.

[anvilvapre]

Illustration,

Moment where the value of now is the same each main loop iteration - i.e. busy loop, no sleeping till next update.

A-axis is now in millis. Count is the number of times the main loop is called.

Zoom in on 2nd spike.

[anvilvapre]

request to put a next-release tag on this. fine if you reject it, for as long as you considered it.