Fix SoundManager::isPlaying to consider multiple entries with the same Ptr/id

Now it returns true if *any* sounds matching the given Ptr and id are playing. The previous behaviour was causing problems with "zombie" sounds (sounds that have finished playing, but weren't removed from the map yet) making the isPlaying method return false even though there's another legitimately playing sound in the map.

apps/openmw/mwsound/soundmanagerimp.cpp

@@ -168,8 +168,8 @@ namespace MWSound
         SoundMap::const_iterator snditer = mActiveSounds.begin();
         while(snditer != mActiveSounds.end())
         {
-            if(snditer->second.first == ptr && snditer->second.second == id)
+            if(snditer->second.first == ptr && snditer->second.second == id && snditer->first->isPlaying())
-                return snditer->first->isPlaying();
+                return true;
             ++snditer;
         }
         return false;