[compiler-rt] [RTSan][Apple] Disable AccessingALargeAtomicVariableDiesWhenRealtime (PR #129309)

[Chris Apple via llvm-commits]

cjappl wrote:

And for completeness:

```
(lldb) break set --name OSSpinLockLock                                                                                         Breakpoint 5: where = libsystem_platform.dylib`OSSpinLockLock, address = 0x000000018d64f518
(lldb) run
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 5.1
    frame #0: 0x000000018d64f518 libsystem_platform.dylib`OSSpinLockLock
libsystem_platform.dylib`OSSpinLockLock:
->  0x18d64f518 <+0>:  mov    w8, #0x0 ; =0
    0x18d64f51c <+4>:  mov    w9, #-0x1 ; =-1
    0x18d64f520 <+8>:  casa   w8, w9, [x0]
    0x18d64f524 <+12>: cmp    w8, #0x0
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 5.1
  * frame #0: 0x000000018d64f518 libsystem_platform.dylib`OSSpinLockLock
    frame #1: 0x000000019a27cb7c libcompiler_rt.dylib`__atomic_load + 184
    frame #2: 0x0000000100003eec a.out`BigStruct std::__1::__cxx_atomic_load[abi:ne180100]<BigStruct>(__a=0x000000016fdfea00, __order=memory_order_seq_cst) at cxx_atomic_impl.h:349:10
    frame #3: 0x0000000100003e64 a.out`std::__1::__atomic_base<BigStruct, false>::load[abi:ne180100](this=0x000000016fdfea00, __m=memory_order_seq_cst) const at atomic_base.h:60:12
    frame #4: 0x0000000100003e0c a.out`main at main.cpp:53:32
    frame #5: 0x000000018d2960e0 dyld`start + 2360
(lldb)
```

https://github.com/llvm/llvm-project/pull/129309