Fix visibility for coroutine types on Windows

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@358551 91177308-0d34-0410-b5e6-96231b3b80d8

include/experimental/coroutine

@@ -81,7 +81,7 @@ struct __coroutine_traits_sfinae<
 };
 
 template <typename _Ret, typename... _Args>
-struct _LIBCPP_TEMPLATE_VIS coroutine_traits
+struct coroutine_traits
     : public __coroutine_traits_sfinae<_Ret>
 {
 };
@@ -298,7 +298,7 @@ noop_coroutine_handle noop_coroutine() _NOEXCEPT {
 }
 #endif // __has_builtin(__builtin_coro_noop)
 
-struct _LIBCPP_TYPE_VIS suspend_never {
+struct suspend_never {
   _LIBCPP_INLINE_VISIBILITY
   bool await_ready() const _NOEXCEPT { return true; }
   _LIBCPP_INLINE_VISIBILITY
@@ -307,7 +307,7 @@ struct _LIBCPP_TYPE_VIS suspend_never {
   void await_resume() const _NOEXCEPT {}
 };
 
-struct _LIBCPP_TYPE_VIS suspend_always {
+struct suspend_always {
   _LIBCPP_INLINE_VISIBILITY
   bool await_ready() const _NOEXCEPT { return false; }
   _LIBCPP_INLINE_VISIBILITY