Negation of user-defined BLAS/LAPACK detection order
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`distutils` allows negation of libraries when determining BLAS/LAPACK
libraries.
This may be used to remove an item from the library resolution phase, i.e.
to disallow NetLIB libraries one could do::

.. code:: bash

    NPY_BLAS_ORDER='^blas' NPY_LAPACK_ORDER='^lapack' python setup.py build

which will use any of the accelerated libraries instead.