Use openblas as BLAS provider
Change blas to a metapackage that depends on a specific implementation (openblas,netlib). Why blas metapackage:
- consistent package, not mixing two different implementations under one package name,
- avoid the confusion with the versions in the future,
- no need to change the dependency on blas.
Add openblas to LCG. Move blas to netlib-blas.