[kcmkwin/rules] Fix kdeinit_kwin_rules_dialog crashing on start

It needs to install the x11connection on the QApplication as it uses
kwinglobals.h internally. Same fix as already done for the KCM, see
305387ec3a.

Thanks to soee on #plasma for reporting the issue just in time to make
Riddell hold the release off.

kcmkwin/kwinrules/main.cpp

@@ -245,6 +245,10 @@ KWIN_EXPORT int kdemain(int argc, char* argv[])
     app.setApplicationDisplayName(i18n("KWin"));
     app.setApplicationName("kwin_rules_dialog");
     app.setApplicationVersion("1.0");
+    if (QX11Info::isPlatformX11()) {
+        app.setProperty("x11Connection", QVariant::fromValue<void*>(QX11Info::connection()));
+        app.setProperty("x11RootWindow", QVariant::fromValue(QX11Info::appRootWindow()));
+    }
     bool whole_app = false;
     bool id_ok = false;
     Window id = None;