[clang] [llvm] Reland: [llvm][clang] Allocate a new stack instead of spawning a new thread to get more stack space (PR #136046)

[David Spickett via cfe-commits]

DavidSpickett wrote:

I've [disabled](https://github.com/llvm/llvm-project/commit/f7fdc8d0cf7cd5caa7d463e1e80e0d5a08c71bb2) the test when threads are disabled.

I don't think it needs to be limited to Apple Silicon actually, because a new OS thread should pass the test (and apparently does). But @Bigcheese please see if you agree with that.

https://github.com/llvm/llvm-project/pull/136046