message: Print warnings to mfem::err
diff: @@ -749,7 +749,7 @@ void CGSolver::Mult(const Vector &b, Vector &x) const
  {
  if (print_options.warnings)
  {
  - mfem::out << "PCG: The preconditioner is not positive definite. (Br, r) = "
  + mfem::err << "PCG: The preconditioner is not positive definite. (Br, r) = "
  << nom << '\n';
  }
  converged = false;
  @@ -773,7 +773,7 @@ void CGSolver::Mult(const Vector &b, Vector &x) const
  {
  if (Dot(d, d) > 0.0 && print_options.warnings)
  {
  - mfem::out << "PCG: The operator is not positive definite. (Ad, d) = "
  + mfem::err << "PCG: The operator is not positive definite. (Ad, d) = "
  << den << '\n';
  }
  if (den == 0.0)
  @@ -808,7 +808,7 @@ void CGSolver::Mult(const Vector &b, Vector &x) const
  {
  if (print_options.warnings)
  {
  - mfem::out << "PCG: The preconditioner is not positive definite. (Br, r) = "
  + mfem::err << "PCG: The preconditioner is not positive definite. (Br, r) = "
  << betanom << '\n';
  }
  converged = false;
  @@ -852,7 +852,7 @@ void CGSolver::Mult(const Vector &b, Vector &x) const
  {
  if (Dot(d, d) > 0.0 && print_options.warnings)
  {
  - mfem::out << "PCG: The operator is not positive definite. (Ad, d) = "
  + mfem::err << "PCG: The operator is not positive definite. (Ad, d) = "
  << den << '\n';
  }
  if (den == 0.0)
  