runtime: make TestWindowsStackMemory build even with CGO_ENABLED=0 set

Just copy some code to make TestWindowsStackMemory build
when CGO_ENABLED is set to 0.

Fixes #22680

Change-Id: I63f9b409a3a97b7718f5d37837ab706d8ed92e81
Reviewed-on: https://go-review.googlesource.com/77430Reviewed-by: Chris Hines <chris.cs.guy@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/runtime/crash_cgo_test.go

@@ -454,7 +454,12 @@ func TestCgoLockOSThreadExit(t *testing.T) {
 	testLockOSThreadExit(t, "testprogcgo")
 }
 
-func testWindowsStackMemory(t *testing.T, o string) {
+func TestWindowsStackMemoryCgo(t *testing.T) {
+	if runtime.GOOS != "windows" {
+		t.Skip("skipping windows specific test")
+	}
+	testenv.SkipFlaky(t, 22575)
+	o := runTestProg(t, "testprogcgo", "StackMemory")
 	stackUsage, err := strconv.Atoi(o)
 	if err != nil {
 		t.Fatalf("Failed to read stack usage: %v", err)
@@ -463,11 +468,3 @@ func testWindowsStackMemory(t *testing.T, o string) {
 		t.Fatalf("expected < %d bytes of memory per thread, got %d", expected, got)
 	}
 }
-
-func TestWindowsStackMemoryCgo(t *testing.T) {
-	if runtime.GOOS != "windows" {
-		t.Skip("skipping windows specific test")
-	}
-	testenv.SkipFlaky(t, 22575)
-	testWindowsStackMemory(t, runTestProg(t, "testprogcgo", "StackMemory"))
-}

src/runtime/syscall_windows_test.go

@@ -15,6 +15,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"syscall"
 	"testing"
@@ -538,7 +539,14 @@ func TestWERDialogue(t *testing.T) {
 }
 
 func TestWindowsStackMemory(t *testing.T) {
-	testWindowsStackMemory(t, runTestProg(t, "testprog", "StackMemory"))
+	o := runTestProg(t, "testprog", "StackMemory")
+	stackUsage, err := strconv.Atoi(o)
+	if err != nil {
+		t.Fatalf("Failed to read stack usage: %v", err)
+	}
+	if expected, got := 100<<10, stackUsage; got > expected {
+		t.Fatalf("expected < %d bytes of memory per thread, got %d", expected, got)
+	}
 }
 
 var used byte