analysis/app: convert to new benchstat library

Change-Id: I80e47f05530260b09dd92a04ddbf4799731ee99c
Reviewed-on: https://go-review.googlesource.com/35944
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Quentin Smith <quentin@golang.org>
diff --git a/benchstat/table.go b/benchstat/table.go
index e5249c1..780e422 100644
--- a/benchstat/table.go
+++ b/benchstat/table.go
@@ -76,7 +76,7 @@
 				new := c.Metrics[k1]
 				// If one is missing, omit row entirely.
 				// TODO: Control this better.
-				if old == new || new == nil {
+				if old == nil || new == nil {
 					continue
 				}
 				pval, testerr := deltaTest(old, new)