new port: math/blis

BLIS is a portable software framework for instantiating high-performance BLAS-like dense linear algebra libraries. The framework was designed to isolate essential kernels of computation that, when optimized, immediately enable optimized implementations of most of its commonly used and computationally intensive operations. BLIS is written in ISO C99 and available under a BSD3CLAUSE. While BLIS exports a new BLAS-like API, it also includes a BLAS compatibility layer which gives application developers access to BLIS implementations via traditional BLAS routine calls. (from their github)

Reviewed by: swills (mentor)
Approved by: swills (mentor)
Differential Revision: https://reviews.freebsd.org/D10811