net: skip TestUnixConnLocalWindows on windows/386

Recent CL 125456 implemented Unix Socket functionality on windows.
But that functionality does not appear to be working when 32-bit
code is used. So disable TestUnixConnLocalWindows.

windows/386 builder does not appear to be complaining about
TestUnixConnLocalWindows, because new functionality requires
Windows 10 Build 17063. windows/386 builder uses Windows 2008.

Fixes #27943

Change-Id: Iea91b86aaa124352d198ca0cd03fff1e7542f949
Reviewed-on: https://go-review.googlesource.com/138676
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Yasuhiro MATSUMOTO <mattn.jp@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/unixsock_windows_test.go

@@ -10,6 +10,7 @@ import (
 	"internal/syscall/windows/registry"
 	"os"
 	"reflect"
+	"runtime"
 	"strconv"
 	"testing"
 )
@@ -33,6 +34,9 @@ func isBuild17063() bool {
 }
 
 func TestUnixConnLocalWindows(t *testing.T) {
+	if runtime.GOARCH == "386" {
+		t.Skip("not supported on windows/386, see golang.org/issue/27943")
+	}
 	if !isBuild17063() {
 		t.Skip("unix test")
 	}