Mk/Uses/blaslapack.mk: Add a flame selector

[jmd]

Summary

This adds an experimental selector to use the Fortran-free, high-performance FLAME libraries math/blis and math/libflame for BLAS and LAPACK, respectively. For the time being, this will only work properly on CURRENT/amd64.

Test Plan

A lot of testing is required before this can be rolled out in production!

[zeising]

From a mentor perspective, this looks OK, however, it probably warrants a exprun, or at least a discussion with portmgr.

As long as portmgr says no, it's no.