New port: devel/py-llvmcpy: Python bindings for LLVM auto-generated from the LLVM-C API

This module allows you to use llvm from Python.
You can use most modern llvm versions, selecting them during runtime.
It uses py-cffi to generate ELF binaries during runtime.

Submitted by: myself
Approved by: tcberner (mentor)
Differential Revision: https://reviews.freebsd.org/D13724