Update go dependencies (#2234)

vendor/github.com/petar/GoLLRB/llrb/llrb-stats.go

@@ -1,46 +0,0 @@
-// Copyright 2010 Petar Maymounkov. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package llrb
-
-// GetHeight() returns an item in the tree with key @key, and it's height in the tree
-func (t *LLRB) GetHeight(key Item) (result Item, depth int) {
-	return t.getHeight(t.root, key)
-}
-
-func (t *LLRB) getHeight(h *Node, item Item) (Item, int) {
-	if h == nil {
-		return nil, 0
-	}
-	if less(item, h.Item) {
-		result, depth := t.getHeight(h.Left, item)
-		return result, depth + 1
-	}
-	if less(h.Item, item) {
-		result, depth := t.getHeight(h.Right, item)
-		return result, depth + 1
-	}
-	return h.Item, 0
-}
-
-// HeightStats() returns the average and standard deviation of the height
-// of elements in the tree
-func (t *LLRB) HeightStats() (avg, stddev float64) {
-	av := &avgVar{}
-	heightStats(t.root, 0, av)
-	return av.GetAvg(), av.GetStdDev()
-}
-
-func heightStats(h *Node, d int, av *avgVar) {
-	if h == nil {
-		return
-	}
-	av.Add(float64(d))
-	if h.Left != nil {
-		heightStats(h.Left, d+1, av)
-	}
-	if h.Right != nil {
-		heightStats(h.Right, d+1, av)
-	}
-}