Ifpack2: MT Gauss-Seidel fixup

James Willenbring requested to merge cgcgcg:MTGS-PR into develop

Created by: cgcgcg

@trilinos/ifpack2 @trilinos/kokkos-kernels


Based on the changes to the MT Gauss-Seidel in kokkos-kernels, this enables damping and the L1 method in Ifpack2's MT GS interface. This deals with the issue that the implementation silently assumed that the matrix diagonal is locally given by indices (i, i), which might not be true for general row and column maps.

This PR includes the changes of https://github.com/kokkos/kokkos-kernels/pull/255, so that they are available before the next promotion of kokkos-kernels (at which point they will be overwritten).

Addresses #2665 (closed), #2768

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