iOS: Handle key window as part of QWindow activation

The default UIWindow may not be the only UIWindow around in a multi
screen setup.

Change-Id: Ia7243190321a1416e577634bf5e010dd67d482e6
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

src/plugins/platforms/ios/qiosapplicationdelegate.mm

@@ -64,7 +64,7 @@
     self.window.backgroundColor = [UIColor cyanColor];
 #endif
 
-    [self.window makeKeyAndVisible];
+    self.window.hidden = NO;
 
     return YES;
 }

src/plugins/platforms/ios/qioswindow.mm

@@ -456,6 +456,8 @@ void QIOSWindow::requestActivateWindow()
     if (!window()->isTopLevel() || blockedByModal())
         return;
 
+    [m_view.window makeKeyWindow];
+
     raise();
     QPlatformInputContext *context = QGuiApplicationPrivate::platformIntegration()->inputContext();
     static_cast<QIOSInputContext *>(context)->focusViewChanged(m_view);