[flang] begin unit testing

Original-commit: flang-compiler/f18@c8b691a4ae7f911363831896ec95684838af19c8
Reviewed-on: https://github.com/flang-compiler/f18/pull/212
Tree-same-pre-rewrite: false
6 files changed
tree: d4c7a1a1eb25e20e8768e70e8510ca302ccae55b
  1. flang/