treewide: use blas and lapack

This makes packages use lapack and blas, which can wrap different
BLAS/LAPACK implementations.

treewide: cleanup from blas/lapack changes

A few issues in the original treewide:

- can’t assume blas64 is a bool
- unused commented code

pkgs/development/libraries/science/math/fenics/default.nix

@@ -24,6 +24,8 @@
 , suitesparse
 , swig
 , zlib
+, blas
+, lapack
 }:
 let
   version = "2019.1.0";
@@ -176,13 +178,14 @@ let
       hdf5
       mpi
       numpy
-      (numpy.blas)
+      blas
+      lapack
       ply
       python
       scotch
       six
       sphinx
-      (suitesparse.override { openblas = numpy.blas; })
+      suitesparse
       swig
       sympy
       ufl