[llvm] Release-mode ML InlineAdvisor

Summary:
This implementation uses a pre-trained model which is statically
compiled into a native function.

RFC: http://lists.llvm.org/pipermail/llvm-dev/2020-April/140763.html

Reviewers: davidxl, jdoerfert, dblaikie

Subscribers: mgorny, eraman, hiraditya, arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81515