OpenBLAS is an optimized BLAS library

Added symbolic link to install a generic blas library that can be used by Octave and R.
OpenBLAS has cpu specific targetted assembly code for speed optimisation.
In most cases, the installation will detect the correct CPU architecture
If you want to specify the architecture you can define the EXTRAPARAMS
environmental variable with EXTRAPARAMS="TARGET=ZEN" (for AMD Ryzen CPUs)