[compiler-rt] [asan][Windows] Synchronizing ASAN init on Windows (PR #74086)

[Vitaly Buka via llvm-commits]

================
@@ -288,11 +298,25 @@ void AsanThread::ThreadStart(tid_t os_id) {
 }
 
 AsanThread *CreateMainThread() {
----------------
vitalybuka wrote:

```
#ifdef // !SANITIZER_WINDOWS
AsanThread *CreateMainThread() {
...
#endif
```

And put windows version into asan_win.cpp

https://github.com/llvm/llvm-project/pull/74086