[clang] [llvm] [llvm][clang] Allocate a new stack instead of spawning a new thread to get more stack space (PR #133173)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

we're seeing the following after this patch:
```
/Volumes/Work/s/w/ir/cache/builder/src/third_party/llvm/llvm/lib/Support/ProgramStack.cpp:67:34: error: this directive must appear between .cfi_startproc and .cfi_endproc directives
   67 |       "add       x29, x0, #0x10\n\t"           // switch to new frame
      |                                  ^
<inline asm>:7:2: note: instantiated into assembly here
    7 |         .cfi_def_cfa w29, 16
      |         ^
/Volumes/Work/s/w/ir/cache/builder/src/third_party/llvm/llvm/lib/Support/ProgramStack.cpp:68:30: error: this directive must appear between .cfi_startproc and .cfi_endproc directives
   68 |       ".cfi_def_cfa w29, 16\n\t"
      |                              ^
<inline asm>:8:2: note: instantiated into assembly here
    8 |         .cfi_offset w30, -8
      |         ^
/Volumes/Work/s/w/ir/cache/builder/src/third_party/llvm/llvm/lib/Support/ProgramStack.cpp:69:29: error: this directive must appear between .cfi_startproc and .cfi_endproc directives
   69 |       ".cfi_offset w30, -8\n\t"                // lr
      |                             ^
<inline asm>:9:2: note: instantiated into assembly here
    9 |         .cfi_offset w29, -16
      |         ^
```

https://github.com/llvm/llvm-project/pull/133173