Renamed DisableWindAudio to MuteWind and made it actually work

This will give Windows(only?) users experiencing the problem with wind sound corruption a way out.

indra/newview/app_settings/settings.xml

@@ -8514,7 +8514,7 @@
         <integer>29</integer>
       </array>
     </map>
-    <key>DisableWindAudio</key>
+    <key>MuteWind</key>
     <map>
       <key>Comment</key>
       <string>Disable the wind audio effect</string>

indra/newview/llvieweraudio.cpp

@@ -271,9 +271,14 @@ void audio_update_wind(bool force_update)
 			// which is sufficient to completely turn off or turn on wind noise
 			volume_delta = 1.f;
 		}
-
+		// mute wind entirely when the user asked
+		if (gSavedSettings.getBOOL("MuteWind"))
+		{
+			// volume decreases by itself
+			gAudiop->mMaxWindGain -= gAudiop->mMaxWindGain;
+		}
 		// mute wind when not /*flying*/ in air
-		if /*(gAgent.getFlying())*/ (gAgentAvatarp && gAgentAvatarp->mInAir)
+		else if /*(gAgent.getFlying())*/ (gAgentAvatarp && gAgentAvatarp->mInAir)
 		{
 			// volume increases by volume_delta, up to no more than max_wind_volume
 			gAudiop->mMaxWindGain = llmin(gAudiop->mMaxWindGain + volume_delta, max_wind_volume);