some fixes to blas/lapack usage in packages (#1852)

* atlas: fix unit test

* openblas: remove symlinks; use lapack_libs.ld_flags in the test

* mkl: fix openmp variant of blas/lapack libs

* intel-parallel-studio: fix openmp variant of blas/lapack libs

* netlib-scalapack: fix blas/lapack for multilib case (e.g. mkl)

* arpack-ng: fix blas/lapack for multilib case (e.g. mkl)

* petsc: explicitly specify blas/lapack

* minor

* cantera: fix blas/lapack usage

* ipopt: fix blas/lapack usage

* netlib-lapack: fix external blas usage

* mfem: fix lapack/blas usage

* superlu-mt: fix blas usage

* flake8 fixes

var/spack/repos/builtin/packages/netlib-lapack/package.py

@@ -91,12 +91,9 @@ def install_one(self, spec, prefix, shared):
             cmake_args.extend(['-DCBLAS=ON'])  # always build CBLAS
 
         if '+external-blas' in spec:
-            # TODO : mechanism to specify the library should be more general,
-            # TODO : but this allows to have an hook to an external blas
             cmake_args.extend([
                 '-DUSE_OPTIMIZED_BLAS:BOOL=ON',
-                '-DBLAS_LIBRARIES:PATH=%s' % join_path(
-                    spec['blas'].prefix.lib, 'libblas.a')
+                '-DBLAS_LIBRARIES:PATH=%s' % spec['blas'].blas_libs.joined(';')
             ])
 
         cmake_args.extend(std_cmake_args)