[clang] [llvm] [OpenMP] Add runtime selection for metadirective with non-constant conditions. (PR #192455)

[Zahira Ammarguellat via cfe-commits]

zahiraam wrote:

Hi @alexey-bataev,

  To make review easier and ensure we strictly follow the plan we agreed on, I'm implementing this incrementally. This implementation is Phase 1 (Parser foundation) only.

  Phase 1:

  1. Detection of non-constant user conditions.
  2. Minimal runtime path in parser.
  3. Path selection logic.
  
  If you agree with this first phase, I will implement next the second one. 
  Thanks.

  

https://github.com/llvm/llvm-project/pull/192455