[clang] [Clang] Reapply CWG2369 "Ordering between constraints and substitution" (PR #122423)

[Alexander Kornienko via cfe-commits]

alexfh wrote:

FYI, we've also seen problems compiling code that includes certain boost headers (version 1.84, as far as I can tell) after https://github.com/llvm/llvm-project/pull/102857:
```
boost/asio/any_io_executor.hpp:161:13: error: satisfaction of constraint '::boost::asio::execution::executor<Executor>' depends on itself
  161 |   template <BOOST_ASIO_EXECUTION_EXECUTOR Executor>
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...
```

I'm building clang with this PR to see if it resolves this issue.

https://github.com/llvm/llvm-project/pull/122423