* Rename voip cvar to cl_voip

* s/#if USE_VOIP/#ifdef USE_VOIP/
* Add generalised runtime cvar range checking, currently on [sv|cl]_voip,
  dedicated and a bunch of r_ variables

code/client/snd_local.h

@@ -140,7 +140,7 @@ typedef struct
 	void (*ClearSoundBuffer)( void );
 	void (*SoundInfo)( void );
 	void (*SoundList)( void );
-#if USE_VOIP
+#ifdef USE_VOIP
 	void (*StartCapture)( void );
 	int (*AvailableCaptureSamples)( void );
 	void (*Capture)( int samples, byte *data );