[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:

Same sort of thing on our Armv8 32-bit build: https://lab.llvm.org/buildbot/#/builders/122/builds/1478
```
../llvm/llvm/unittests/Support/ProgramStackTest.cpp:32
Expected: (StackDistance) > (llvm::sys::Process::getPageSizeEstimate()), actual: 8 vs 4096
```


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