QueryParser: Don't send notifications if the node's been deleted.

Gets rid of redundant messages under B_QUERY_WATCH_ALL.

src/add-ons/kernel/file_systems/bfs/Query.cpp

@@ -283,6 +283,11 @@ struct Query::QueryPolicy {
 		return NULL;
 	}
 
+	static bool NodeIsDeleted(Node* node)
+	{
+		return node->IsDeleted();
+	}
+
 	// Volume interface
 
 	static dev_t ContextGetVolumeID(Context* context)

src/add-ons/kernel/file_systems/packagefs/indices/Query.cpp

@@ -220,6 +220,11 @@ struct Query::QueryPolicy {
 		return NULL;
 	}
 
+	static bool NodeIsDeleted(Node* node)
+	{
+		return node->GetParentUnchecked() == NULL;
+	}
+
 	// Volume interface
 
 	static dev_t ContextGetVolumeID(Context* context)

src/add-ons/kernel/file_systems/ramfs/Query.cpp

@@ -276,6 +276,11 @@ struct Query::QueryPolicy {
 		return node->GetNextReferrer(entry);
 	}
 
+	static bool NodeIsDeleted(Node* node)
+	{
+		return node->GetFirstReferrer() == NULL;
+	}
+
 	// Volume interface
 
 	static dev_t ContextGetVolumeID(Context* context)