removed getStreamLatency() from derived API classes

RtAudio.h

@@ -902,7 +902,6 @@ public:
   void startStream( void );
   void stopStream( void );
   void abortStream( void );
-  long getStreamLatency( void );
 
   // This function is intended for internal use only.  It must be
   // public because it is called by the internal callback handler,
@@ -938,7 +937,6 @@ public:
   void startStream( void );
   void stopStream( void );
   void abortStream( void );
-  long getStreamLatency( void );
 
   // This function is intended for internal use only.  It must be
   // public because it is called by the internal callback handler,
@@ -973,7 +971,6 @@ public:
   void startStream( void );
   void stopStream( void );
   void abortStream( void );
-  long getStreamLatency( void );
 
   // This function is intended for internal use only.  It must be
   // public because it is called by the internal callback handler,
@@ -1011,7 +1008,6 @@ public:
   void startStream( void );
   void stopStream( void );
   void abortStream( void );
-  long getStreamLatency( void );
 
   // This function is intended for internal use only.  It must be
   // public because it is called by the internal callback handler,