KokkosKernels,Tpetra: Plug in TPLs (MKL, cuSPARSE, ...) for sparse matrix-matrix multiply
Created by: mhoemmen
@trilinos/tpetra @trilinos/muelu @mndevec @csiefer2
See #147 (closed) for discussion. Depends on #148 (closed) (otherwise we can't plug in a local kernel). Depends on #415 (MKL sparse matrix-matrix multiply wants to own deallocation of the result matrix's arrays, so Kokkos can't own them; deallocation has to happen in the handle)