Support for Cray's LibSci library, which provides BLAS/LAPACK support.
cfr. https://www.nersc.gov/users/software/programming-libraries/math-libraries/libsci/
Filter BLAS module from toolchain definition.
The cray-libsci module is loaded indirectly (and versionless) via the PrgEnv module,
and thus is not a direct toolchain component.