package/armadillo: allow to select between lapack or openblas

package/armadillo: allow to select between lapack or openblas

armadillo can use lapack or openblas as BLAS provider. LAPACK support is
optional.

This patch
- adds an _ARCH_SUPPORTS variable to check if one is available
- adds an option to choose lapack or openblas as BLAS provider

The choice is required since applications may potentially need lapack.

Signed-off-by: Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>