net/http/cgi: make tests compile on plan9

Don't reference the non-portable syscall.Signal(0).

Maybe they'll pass too. Untested. plan9 bit from
Akshat Kumar.

R=golang-dev, akumar
CC=golang-dev
https://golang.org/cl/7370049

src/pkg/net/http/cgi/host_test.go

@@ -19,7 +19,6 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
-	"syscall"
 	"testing"
 	"time"
 )
@@ -340,11 +339,7 @@ func TestCopyError(t *testing.T) {
 	}
 
 	childRunning := func() bool {
-		p, err := os.FindProcess(pid)
-		if err != nil {
-			return false
-		}
-		return p.Signal(syscall.Signal(0)) == nil
+		return isProcessRunning(t, pid)
 	}
 
 	if !childRunning() {

src/pkg/net/http/cgi/plan9_test.go

@@ -0,0 +1,18 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build plan9
+
+package cgi
+
+import (
+	"os"
+	"strconv"
+	"testing"
+)
+
+func isProcessRunning(t *testing.T, pid int) bool {
+	_, err := os.Stat("/proc/" + strconv.Itoa(pid))
+	return err == nil
+}

src/pkg/net/http/cgi/posix_test.go

@@ -0,0 +1,21 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !plan9
+
+package cgi
+
+import (
+	"os"
+	"syscall"
+	"testing"
+)
+
+func isProcessRunning(t *testing.T, pid int) bool {
+	p, err := os.FindProcess(pid)
+	if err != nil {
+		return false
+	}
+	return p.Signal(syscall.Signal(0)) == nil
+}