WinRT: emit SDL_APP_TERMINATING

src/core/winrt/SDL_winrtapp_direct3d.cpp

@@ -259,6 +259,9 @@ void SDL_WinRTApp::Initialize(CoreApplicationView^ applicationView)
     CoreApplication::Resuming +=
         ref new EventHandler<Platform::Object^>(this, &SDL_WinRTApp::OnResuming);
 
+    CoreApplication::Exiting +=
+        ref new EventHandler<Platform::Object^>(this, &SDL_WinRTApp::OnExiting);
+
     DisplayProperties::OrientationChanged +=
         ref new DisplayPropertiesEventHandler(this, &SDL_WinRTApp::OnOrientationChanged);
 
@@ -578,6 +581,11 @@ void SDL_WinRTApp::OnResuming(Platform::Object^ sender, Platform::Object^ args)
     }
 }
 
+void SDL_WinRTApp::OnExiting(Platform::Object^ sender, Platform::Object^ args)
+{
+    SDL_SendAppEvent(SDL_APP_TERMINATING);
+}
+
 static void
 WINRT_LogPointerEvent(const char * header, Windows::UI::Core::PointerEventArgs ^ args, Windows::Foundation::Point transformedPoint)
 {

src/core/winrt/SDL_winrtapp_direct3d.h

@@ -35,6 +35,7 @@ protected:
     void OnActivated(Windows::ApplicationModel::Core::CoreApplicationView^ applicationView, Windows::ApplicationModel::Activation::IActivatedEventArgs^ args);
     void OnSuspending(Platform::Object^ sender, Windows::ApplicationModel::SuspendingEventArgs^ args);
     void OnResuming(Platform::Object^ sender, Platform::Object^ args);
+    void OnExiting(Platform::Object^ sender, Platform::Object^ args);
     void OnWindowClosed(Windows::UI::Core::CoreWindow^ sender, Windows::UI::Core::CoreWindowEventArgs^ args);
     void OnVisibilityChanged(Windows::UI::Core::CoreWindow^ sender, Windows::UI::Core::VisibilityChangedEventArgs^ args);
     void OnPointerPressed(Windows::UI::Core::CoreWindow^ sender, Windows::UI::Core::PointerEventArgs^ args);