Fix segfault when complex double matrix calls ZGETRF (bug #45577). * CMatrix.cc (finverse, determinant, rcond, fsolve): Calculate norm of matrix and if it is NaN, skip calling ZGETRF in LAPACK and set info to non-zero value to signal an error.

# scope1.m
function scope1 (n)
  value = n;
  if value
    C;
  end
  function A
    B;
    function B
      scope1 (0);
    endfunction
  endfunction

  function C
    D;
    function D
      A;
    endfunction
  endfunction
endfunction