WIP: Use LAPACK 2.0 xLAHQR (#6965)

Test case - Comment 10 in http://forge.scilab.org/index.php/p/arpack-ng/issues/1315/
````
A = [
  1.0   1.0   1.0   1.0   1.0   1.0   1.0  1.0
 -1.0   2.0   0.0   0.0   0.0   0.0   0.0  1.0
 -1.0   0.0   3.0   0.0   0.0   0.0   0.0  1.0
 -1.0   0.0   0.0   4.0   0.0   0.0   0.0  1.0
 -1.0   0.0   0.0   0.0   5.0   0.0   0.0  1.0
 -1.0   0.0   0.0   0.0   0.0   6.0   0.0  1.0
 -1.0   0.0   0.0   0.0   0.0   0.0   7.0  1.0
 -1.0  -1.0  -1.0  -1.0  -1.0  -1.0  -1.0  8.0
]
````
Expected result according to MATLAB-8.2 / OCTAVE for `eigs(A, nev=2, which="SM")` is
````
octave:3> eigs(A, 2, "sm")
ans =

   2.5347 + 0.0000i
   2.6160 + 1.2918i

````