AlchSync: Change dynamic_casts to LLVOVolume to asVolume()

indra/newview/llviewerobject.cpp

@@ -3091,7 +3091,7 @@ void LLViewerObject::linkControlAvatar()
 {
 	if (!getControlAvatar() && isRootEdit())
 	{
-		LLVOVolume *volp = dynamic_cast<LLVOVolume*>(this);
+        LLVOVolume *volp = asVolume();
 		if (!volp)
 		{
 			LL_WARNS() << "called with null or non-volume object" << LL_ENDL;
@@ -5583,6 +5583,12 @@ LLVOAvatar* LLViewerObject::asAvatar()
 	return NULL;
 }
 
+// virtual 
+LLVOVolume* LLViewerObject::asVolume()
+{
+	return nullptr;
+}
+
 // If this object is directly or indirectly parented by an avatar,
 // return it.  Normally getAvatar() is the correct function to call;
 // it will give the avatar used for skinning.  The exception is with