Old VWR-14914 spin-off sound beacon patch.

This makes sound beacons green when playing at
full volume, yellow when playing at a lower volume
and red when they are muted (aka, in another parcel
that you can't hear the sounds of).

Originally this was a debug patch as muted sound
sources used to be implemented by setting the volume
to zero, which happens to use like three times more
CPU: so, having a lot of muted sound source caused
the audio thread to never release a mutex anymore
(cause it was never idle anymore), causing the main
loop to hang, waiting on that mutex - dropping the
FPS drastically. Hence it was necessary to see which
sound sources were muted for debugging purposes.
(Since VWR-14914, muted source source are not played
at all anymore, so they do not take extra CPU).

It's still fun to see this extra information though,
now the patch exists anyway.

indra/newview/llviewerwindow.cpp

@@ -553,7 +553,7 @@ public:
 				}
 			if (LLPipeline::getRenderSoundBeacons(NULL))
 			{
-				addText(xpos, ypos, "Viewing sound beacons (yellow)");
+				addText(xpos, ypos, "Viewing sound beacons (blue/cyan/green/yellow/red)");
 				ypos += y_inc;
 			}
 		}