[compiler-rt] [compiler-rt] Use __atomic builtins whenever possible (PR #84439)

[Dmitry Vyukov via llvm-commits]

dvyukov wrote:

> On x86 I don't see any difference for __tsan_read*/__tsan_write* in the x86 assembly (other than the relative addresses) > __tsan_func_entry/exit.

Thanks for double checking.
If  __tsan_read*/__tsan_write* are not negatively affected, then it's good enough for me.
Change in _ZN11__sanitizer23InternalAllocatorUnlockEv looks fine, if compiler thinks it's better.

https://github.com/llvm/llvm-project/pull/84439