Avoid using API introduced in Qt 5.5

Especially, QMetaEnum::fromType() and friends. Tracking which kinds of
messages were actually generated is better anyway, as we don't get
empty rows like this.

Change-Id: I23c560d9071c0ff5a33dff660e4dbb1552890df8
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

plugins/qmlprofiler/debugmessagesmodel.h

@@ -45,6 +45,8 @@ public:
     QVariantMap location(int index) const override;
 
 private:
+    static QString messageType(uint i);
+
     struct MessageData {
         MessageData(const QString &text = QString(), int typeId = -1) :
             text(text), typeId(typeId) {}
@@ -52,6 +54,7 @@ private:
         int typeId;
     };
 
+    int m_maximumMsgType;
     QVector<MessageData> m_data;
 };