[asan][win] Fix CreateThread leak (llvm#126738)

Fix llvm#126541

Since ```t->Destroy``` cannot be called after ```start_routine```(When
calling standard thread_start in crt)

Intercept `ExitThread` and free the memory created by `VirtualAlloc'

Author: GkvJwa

compiler-rt/lib/asan/asan_win.cpp

@@ -145,7 +145,6 @@ static thread_return_t THREAD_CALLING_CONV asan_thread_start(void *arg) {
   t->GetStartData(params);
 
   auto res = (*params.start_routine)(params.arg);
-  t->Destroy();  // POSIX calls this from TSD destructor.
   return res;
 }
 
@@ -166,6 +165,13 @@ INTERCEPTOR_WINAPI(HANDLE, CreateThread, LPSECURITY_ATTRIBUTES security,
                             thr_flags, tid);
 }
 
+INTERCEPTOR_WINAPI(void, ExitThread, DWORD dwExitCode) {
+  AsanThread *t = (AsanThread *)__asan::GetCurrentThread();
+  if (t)
+    t->Destroy();
+  REAL(ExitThread)(dwExitCode);
+}
+
 // }}}
 
 namespace __asan {
@@ -181,6 +187,7 @@ void InitializePlatformInterceptors() {
       (LPCWSTR)&InitializePlatformInterceptors, &pinned));
 
   ASAN_INTERCEPT_FUNC(CreateThread);
+  ASAN_INTERCEPT_FUNC(ExitThread);
   ASAN_INTERCEPT_FUNC(SetUnhandledExceptionFilter);
 
 #ifdef _WIN64