AMD equivalent to NvOptimusEnablement

According to https://community.amd.com/thread/169965

extern "C" { __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1; }

This will select the high performance GPU as long as no profile exists that assigns the application to another GPU.

Please make sure to use a 13.35 or newer driver. Older drivers do not support this.