RCORE: tests: use std::atomic and atomic_load/store instead of Atomic<>
RCORE: tests: use std::atomic and atomic_load/store instead of Atomic<>

Signed-off-by: Tim Janik <6ec6ff229c4e1c5bbd5933ee92e6c5832ff023bb@gnu.org>

tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn