test: say that nilptr2.go requires 256+MB stack
Fixes #6161.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13059043
diff --git a/test/nilptr2.go b/test/nilptr2.go
index 3d9ca0a..57a5f80 100644
--- a/test/nilptr2.go
+++ b/test/nilptr2.go
@@ -87,8 +87,8 @@
 	{"&bigstructp.x[i]", func() { println(&bigstructp.x[i]) }},
 	{"bigstructp.x[9]", func() { println(bigstructp.x[9]) }},
 	{"&bigstructp.x[9]", func() { println(&bigstructp.x[9]) }},
-	{"bigstructp.x[200<<20]", func() { println(bigstructp.x[200<<20]) }},
-	{"&bigstructp.x[200<<20]", func() { println(&bigstructp.x[200<<20]) }},
+	{"bigstructp.x[100<<20]", func() { println(bigstructp.x[100<<20]) }},
+	{"&bigstructp.x[100<<20]", func() { println(&bigstructp.x[100<<20]) }},
 	{"bigstructp.l", func() { println(bigstructp.l) }},
 	{"&bigstructp.l", func() { println(&bigstructp.l) }},
 	{"m1.F()", func() { println(m1.F()) }},
@@ -109,7 +109,7 @@
 	i int
 	j float64
 	k string
-	x [256<<20]byte
+	x [128<<20]byte
 	l []byte
 }