Revert "[libc++] Don't try to wait on a thread that hasn't started in std::async (#125433)"

This reverts commit 11766a4.

Author: kadircet

libcxx/include/future

@@ -865,8 +865,7 @@ void __async_assoc_state<_Rp, _Fp>::__execute() {
 
 template <class _Rp, class _Fp>
 void __async_assoc_state<_Rp, _Fp>::__on_zero_shared() _NOEXCEPT {
-  if (base::__state_ & base::__constructed)
-    this->wait();
+  this->wait();
   base::__on_zero_shared();
 }
 
@@ -903,8 +902,7 @@ void __async_assoc_state<void, _Fp>::__execute() {
 
 template <class _Fp>
 void __async_assoc_state<void, _Fp>::__on_zero_shared() _NOEXCEPT {
-  if (base::__state_ & base::__constructed)
-    this->wait();
+  this->wait();
   base::__on_zero_shared();
 }