Initial investigation into API design for user-specified determinism guarantees in Thrust and PSTL

[jrhemstad]

User can require determinism from CUB interface but not Thrust or PSTL. We have to design a way to attach determinism requirement to execution policy.

[gonidelis]

@jrhemstad Not sure if this is becoming obsolete now that we have settled to an environment API.

[gevtushenko]

@gonidelis we have environments API for CUB. This issue doesn't seem CUB specific. Let's consider it done when we know how to specify determinism in Thrust and parallel algorithms in cuda:: .