Trouble compiling with NVCC, restrict and variadic parameter packs

I've been having trouble compiling my test programs with NVCC 11.x; see [this SO question](https://stackoverflow.com/questions/69018930/nvcc-wont-compile-perfect-forwarding-with-restrict-and-parameter-packs?noredirect=1#comment121982267_69018930).

A workaround for the problem is dropping all of the `__restrict__` qualifiers. We don't really care about them anyway.