clutter/frame-clock: Increase EstimateQueue length from 16 to 256 frames
The problem with a short queue length is that it never learns about periodic peaks in render time that are less frequent than once in 16 frames. For example, a clock drawing once per second - every 60th frame.
Increase the queue length to 256 so we learn the correct max render time for slow periodic peaks. This will cover the ticking clock case for any monitor up to 256Hz and avoids a frame skip when the tick happens.
Fixes: gnome-shell#4830 (closed)