[libc++][NFC] Fixed some wrongly spelled _LIBCPP_STD_VER in comments (#147008)

Author: H-G-Hristov

libcxx/include/__coroutine/coroutine_handle.h

@@ -172,6 +172,6 @@ struct hash<coroutine_handle<_Tp>> {
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // __LIBCPP_STD_VER >= 20
+#endif // _LIBCPP_STD_VER >= 20
 
 #endif // _LIBCPP___COROUTINE_COROUTINE_HANDLE_H

libcxx/include/__coroutine/coroutine_traits.h

@@ -43,6 +43,6 @@ struct coroutine_traits : public __coroutine_traits_sfinae<_Ret> {};
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // __LIBCPP_STD_VER >= 20
+#endif // _LIBCPP_STD_VER >= 20
 
 #endif // _LIBCPP___COROUTINE_COROUTINE_TRAITS_H

libcxx/include/__coroutine/noop_coroutine_handle.h

@@ -94,6 +94,6 @@ inline _LIBCPP_HIDE_FROM_ABI noop_coroutine_handle noop_coroutine() noexcept { r
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // __LIBCPP_STD_VER >= 20
+#endif // _LIBCPP_STD_VER >= 20
 
 #endif // _LIBCPP___COROUTINE_NOOP_COROUTINE_HANDLE_H

libcxx/include/__coroutine/trivial_awaitables.h

@@ -35,6 +35,6 @@ struct suspend_always {
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // __LIBCPP_STD_VER >= 20
+#endif // _LIBCPP_STD_VER >= 20
 
 #endif // __LIBCPP___COROUTINE_TRIVIAL_AWAITABLES_H