Fix plugins/qpa build with Qt 5.13

Summary:
Upstream moved screen maintenance functions from
QPlatformIntegration to QWSI.

BUG: 406056
See also: https://code.qt.io/cgit/qt/qtbase.git/commit/?h=5.13&id=01e1df90

Test Plan: Built fine with Qt 5.12.2 and Qt 5.13 stable branch.

Reviewers: #kwin, zzag

Reviewed By: #kwin, zzag

Subscribers: zzag, arojas, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D20239

plugins/qpa/integration.cpp

@@ -98,7 +98,11 @@ void Integration::initialize()
     );
     QPlatformIntegration::initialize();
     auto dummyScreen = new Screen(-1);
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 13, 0))
+    QWindowSystemInterface::handleScreenAdded(dummyScreen);
+#else
     screenAdded(dummyScreen);
+#endif
     m_screens << dummyScreen;
     m_inputContext.reset(QPlatformInputContextFactory::create(QStringLiteral("qtvirtualkeyboard")));
     qunsetenv("QT_IM_MODULE");
@@ -207,16 +211,28 @@ void Integration::initScreens()
     newScreens.reserve(qMax(screens()->count(), 1));
     for (int i = 0; i < screens()->count(); i++) {
         auto screen = new Screen(i);
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 13, 0))
+        QWindowSystemInterface::handleScreenAdded(screen);
+#else
         screenAdded(screen);
+#endif
         newScreens << screen;
     }
     if (newScreens.isEmpty()) {
         auto dummyScreen = new Screen(-1);
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 13, 0))
+        QWindowSystemInterface::handleScreenAdded(dummyScreen);
+#else
         screenAdded(dummyScreen);
+#endif
         newScreens << dummyScreen;
     }
     while (!m_screens.isEmpty()) {
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 13, 0))
+        QWindowSystemInterface::handleScreenRemoved(m_screens.takeLast());
+#else
         destroyScreen(m_screens.takeLast());
+#endif
     }
     m_screens = newScreens;
 }