message: Pull back cmake and C++ upgrade for now. Will reintroduce it in a
  later change.
diff: # -*- mode:cmake -*-
  -cmake_minimum_required(VERSION 3.15)
  +cmake_minimum_required(VERSION 3.5.1)
  # Detect build type, fallback to release and throw a warning if use didn't
  # specify any
  @@ -30,7 +30,7 @@ add_subdirectory(third_party/antlr4/runtime/Cpp EXCLUDE_FROM_ALL)
  add_subdirectory(third_party/UHDM)
  add_subdirectory(third_party/googletest EXCLUDE_FROM_ALL)
  -set(CMAKE_CXX_STANDARD 17)
  +set(CMAKE_CXX_STANDARD 11)
  set(CMAKE_CXX_STANDARD_REQUIRED ON)
  set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
  