Test validity of permutation used for SymGS

[maherou]

Presently we trust that the optimized implementation of SymGS accurately keeps all entries of the sparse triangular system when performing the permuted operation. Lost entries, which could increase parallelism and affect convergence, but have a net positive impact on performance, are not specifically tested for. By requesting the permutation vector used for the optimized SymGS we can test for dropped entries using the reference kernels with the permuted vectors.