Tpetra: Add iallreduce overload that takes raw pointers
Created by: mhoemmen
@trilinos/tpetra @cgcgcg
PR https://github.com/trilinos/Trilinos/pull/4057 creates nonowning length-1 Kokkos::View
s merely because the interface of Tpetra::Details::iallreduce
demands it. Users will want to pass raw pointers into iallreduce
, so we might as well give them an interface that supports it.