Core: Handle async log category init

If a log category is first used by a different thread than the main
thread, we need to make sure that we dispatch the call into the
main thread ourselves.

Change-Id: I0908366b254649f30a1d18cb4e0da4a7e3988dcc
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/coreplugin/loggingviewer.cpp

@@ -95,6 +95,12 @@ private:
 
     void onFilter(QLoggingCategory *category)
     {
+        if (QThread::currentThread() != thread()) {
+            QMetaObject::invokeMethod(
+                this, [category, this] { onFilter(category); }, Qt::QueuedConnection);
+            return;
+        }
+
         if (!m_categories.contains(category)) {
             m_categories.append(category);
             emit newLogCategory(category);