Rendering issues with AMD GPUs due to unsafe default settings

[PMunkes]

The current default settings for OpenCL cause rendering issues on AMD GPUs. These issues occur for multiple driver versions since at least 19.12.2 to current with several different GPUs (RX 480, Vega56, RX 5700XT and RX 6800.) The issues stem from the default setting -cl-fast-relaxed-math. Source

This setup explicitly allows the compiler to perform unsafe and not standard-compliant math optimizations, and as such this should not be the default setting.
Disabling the setting fixes the rendering issues.

Default:

-cl-fast-relaxed-math disabled: