Add new port math/viennacl

ViennaCL is a free open-source linear algebra library for computations on many-core
architectures (GPUs, MIC) and multi-core CPUs. The library is written in C++ and
supports CUDA, OpenCL, and OpenMP (including switches at runtime).

http://viennacl.sourceforge.net/

PR: 219714
Submitted by: pfg