C++ editor: Prefer to use extra selections to find diagnostics.

Change-Id: I5f1c6e29c8386018cfd4d45d8ee63fc3e24311f6
Reviewed-on: http://codereview.qt.nokia.com/3484
Reviewed-by: Leandro T. C. Melo <leandro.melo@nokia.com>

src/plugins/cpptools/cppmodelmanager.cpp

@@ -1084,6 +1084,7 @@ void CppModelManager::onDocumentUpdated(Document::Ptr doc)
                 }
                 c.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);
                 sel.cursor = c;
+                sel.format.setToolTip(m.text());
                 selections.append(sel);
             }
 #endif