ensure important docs are built by the automated publisher

this workaround makes sure that qdoc can find the \class
and \namespace declarations.

Change-Id: I950e6fbc10064f438d7f282ff20783acdf20de27
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/multimedia/audio/qaudio.h

@@ -56,6 +56,8 @@ QT_MODULE(Multimedia)
 
 //QTM_SYNC_HEADER_EXPORT QAudio
 
+// Class forward declaration required for QDoc bug
+class QString;
 namespace QAudio
 {
     enum Error { NoError, OpenError, IOError, UnderrunError, FatalError };