[Lapack] [lapackers] bug in DGEHRD

[Julien Langou]

> > > There is a permutation that makes this matrix 2x2 block triangular,
> > Mmm, I can not find this permutation ...
> I found the permutation that makes the matrix block-triangular by eyeball,
> based on the Kronecker-product-like spyplot of the matrix:
> [ ... ]
> This makes it block lower triangular where the first block is 24x24 and
> the second 4x4.
well, so long, for the 2x2 block triangularity then ....