WinRT: Initialize platform services

platformServices has not been created and caused a crash as soon as an
URL gets opened.

Task-number: QTBUG-48740
Change-Id: Ib099a0ff3007b168738e02c0fab8f9ca7bcd25c7
Reviewed-by: Andrew Knight <andrew.knight@intopalo.com>

src/plugins/platforms/winrt/qwinrtintegration.cpp

@@ -151,6 +151,8 @@ QWinRTIntegration::QWinRTIntegration() : d_ptr(new QWinRTIntegrationPrivate)
         return S_OK;
     });
     Q_ASSERT_SUCCEEDED(hr);
+
+    d->platformServices = new QWinRTServices;
 }
 
 QWinRTIntegration::~QWinRTIntegration()