move constants from backend to AudioRenderer

engine/renderers/AudioRenderer.h

@@ -40,6 +40,12 @@ typedef Id SoundSourceId;
 
 class AudioRenderer
 {
+public:
+
+	static const uint32_t	MAX_SOURCES = 128;
+	static const uint32_t	MAX_BUFFERS_PER_SOURCES = 16;
+	static const uint32_t 	MAX_BUFFERS = MAX_SOURCES * MAX_BUFFERS_PER_SOURCES;
+	
 public:
 
 	static AudioRenderer*	create(Allocator& a);