build: be verbose when running tests on Plan 9

This is a temporary change to see how far the
builder gets when it times out.

LGTM=aram, 0intro
R=0intro, aram
CC=golang-codereviews, mischief
https://golang.org/cl/111400043

src/run.rc

@@ -54,7 +54,7 @@ go test ../test/bench/go1
 
 @{
 	xcd ../test
-	GOMAXPROCS='' time go run run.go
+	GOMAXPROCS='' time go run run.go -v
 }
 
 echo