Fix the column permutation in SparseQR
Move SparseColEtree common to SparseLU and SparseQR to SparseCore and fix build issue of sparseqr

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rename : Eigen/src/SparseLU/SparseLU_Coletree.h => Eigen/src/SparseCore/SparseColEtree.h
Delete unused variable in SparseLU