cmd/release: notify explorer of PATH update after install on Win

Windows installer will not broadcast WM_SETTINGCHANGE when a reboot is
pending. This message is required for explorer.exe to reload the PATH
from the registry so future cmd.exe processes will launch with go/bin in
the PATH.

- Updated to wix v3.11[1]
- Added sha256 validation of wix binary after download
- Use the Wix extension[0] to always broadcast WM_SETTINGCHANGE after install.
- Removed to RegistryKey/@action in installer.wxs suppress warning CNDL1138.
  The param is deperacated and not needed.

[0] http://wixtoolset.org/documentation/manual/v3/customactions/wixsettingchange.html
[1] https://github.com/wixtoolset/wix3/releases/tag/wix311rtm

Fixes golang/go#18680

Change-Id: I645b1e4a32bf0c1df2925d53474a38a7d7ddec94
Reviewed-on: https://go-review.googlesource.com/46458
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/release/releaselet.go

@@ -11,7 +11,9 @@ package main
 import (
 	"archive/zip"
 	"bytes"
+	"crypto/sha256"
 	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
@@ -291,7 +293,8 @@ func windowsMSI() error {
 	)
 }
 
-const wixBinaries = "https://storage.googleapis.com/go-builder-data/wix35-binaries.zip"
+const wixBinaries = "https://storage.googleapis.com/go-builder-data/wix311-binaries.zip"
+const wixSha256 = "da034c489bd1dd6d8e1623675bf5e899f32d74d6d8312f8dd125a084543193de"
 
 // installWix fetches and installs the wix toolkit to the specified path.
 func installWix(path string) error {
@@ -301,6 +304,12 @@ func installWix(path string) error {
 		return err
 	}
 
+	// Verify sha256
+	sum := sha256.Sum256(body)
+	if fmt.Sprintf("%x", sum) != wixSha256 {
+		return errors.New("sha256 mismatch for wix toolkit")
+	}
+
 	// Unzip to path.
 	zr, err := zip.NewReader(bytes.NewReader(body), int64(len(body)))
 	if err != nil {
@@ -632,8 +641,7 @@ var windowsData = map[string]string{
   <Component Id="Component_GoEnvironment" Guid="{3ec7a4d5-eb08-4de7-9312-2df392c45993}">
     <RegistryKey
         Root="HKCU"
-        Key="Software\GoProgrammingLanguage"
-        Action="create" >
+        Key="Software\GoProgrammingLanguage">
             <RegistryValue
                 Name="installed"
                 Type="integer"
@@ -681,6 +689,9 @@ var windowsData = map[string]string{
     <Custom Action="SetApplicationRootDirectory" Before="InstallFinalize" />
 </InstallExecuteSequence>
 
+<!-- Notify top level applications of the new PATH variable (golang.org/issue/18680)  -->
+<CustomActionRef Id="WixBroadcastEnvironmentChange" />
+
 <!-- Include the user interface -->
 <WixVariable Id="WixUILicenseRtf" Value="LICENSE.rtf" />
 <WixVariable Id="WixUIBannerBmp" Value="images\Banner.jpg" />