message: Fix windows x86_64 binaryen toolchain download URL
diff: @@ -171,7 +171,7 @@ fn prebuilt_url(tool: &Tool, version: &str) -> Result<String, failure::Error> {
  "x86_64-macos"
  } else if target::WINDOWS && target::x86_64 {
  match tool {
  - Tool::WasmOpt => "x86-windows",
  + Tool::WasmOpt => "x86_64-windows",
  _ => "x86_64-pc-windows-msvc",
  }
  } else if target::WINDOWS && target::x86 {
  