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>
1 file changed