Fix for crash bug in SPQRSupport: Initialize pointers to nullptr to avoid free() calls of invalid pointers.

(cherry picked from commit 550af3938cc46116435f3dd88a9cdc94837d7542)

Eigen/src/SPQRSupport/SuiteSparseQRSupport.h

@@ -258,12 +258,12 @@ class SPQR : public SparseSolverBase<SPQR<_MatrixType> >
     int m_ordering; // Ordering method to use, see SPQR's manual
     int m_allow_tol; // Allow to use some tolerance during numerical factorization.
     RealScalar m_tolerance; // treat columns with 2-norm below this tolerance as zero
-    mutable cholmod_sparse *m_cR; // The sparse R factor in cholmod format
+    mutable cholmod_sparse *m_cR = nullptr; // The sparse R factor in cholmod format
     mutable MatrixType m_R; // The sparse matrix R in Eigen format
-    mutable StorageIndex *m_E; // The permutation applied to columns
-    mutable cholmod_sparse *m_H;  //The householder vectors
-    mutable StorageIndex *m_HPinv; // The row permutation of H
-    mutable cholmod_dense *m_HTau; // The Householder coefficients
+    mutable StorageIndex *m_E = nullptr; // The permutation applied to columns
+    mutable cholmod_sparse *m_H = nullptr;  //The householder vectors
+    mutable StorageIndex *m_HPinv = nullptr; // The row permutation of H
+    mutable cholmod_dense *m_HTau = nullptr; // The Householder coefficients
     mutable Index m_rank; // The rank of the matrix
     mutable cholmod_common m_cc; // Workspace and parameters
     bool m_useDefaultThreshold;     // Use default threshold