Fix some compiler warnings.

As it turns out, we had an overloaded virtual from an earlier era,
with the extra parameter never used.  So cleaning that up was a
bonus to remove the compiler warning.

Change-Id: I780287f8a5d2b0a1ec84ec62c88ba50e051f372b
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

examples/spectrum/app/wavfile.h

@@ -51,6 +51,7 @@ class WavFile : public QFile
 public:
     WavFile(QObject *parent = 0);
 
+    using QFile::open;
     bool open(const QString &fileName);
     const QAudioFormat &fileFormat() const;
     qint64 headerLength() const;