Ensure race condition workaround is applied for all CVDisplayLinkStops.
Ensure race condition workaround is applied for all CVDisplayLinkStops.

This also centralises the workaround, the better for replacing it when I discover a safer alternative.

TomHarte/CLK,TomHarte/CLK,TomHarte/CLK,TomHarte/CLK,TomHarte/CLK