windows: use netevent.dll in TestFormatMessage for windows/arm

pdh.dll is not available on Windows IoT core. Use netevent.dll instead.

Update golang/go#26148

Change-Id: I80c299ad030944954d5d7d182d91dc15e71341f9
Reviewed-on: https://go-review.googlesource.com/c/154560Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

windows/syscall_windows_test.go

@@ -10,7 +10,6 @@ import (
 	"path/filepath"
 	"syscall"
 	"testing"
-	"unsafe"
 
 	"golang.org/x/sys/windows"
 )
@@ -54,34 +53,14 @@ func TestWin32finddata(t *testing.T) {
 }
 
 func TestFormatMessage(t *testing.T) {
-	dll := windows.MustLoadDLL("pdh.dll")
-
-	pdhOpenQuery := func(datasrc *uint16, userdata uint32, query *windows.Handle) (errno uintptr) {
-		r0, _, _ := syscall.Syscall(dll.MustFindProc("PdhOpenQueryW").Addr(), 3, uintptr(unsafe.Pointer(datasrc)), uintptr(userdata), uintptr(unsafe.Pointer(query)))
-		return r0
-	}
-
-	pdhCloseQuery := func(query windows.Handle) (errno uintptr) {
-		r0, _, _ := syscall.Syscall(dll.MustFindProc("PdhCloseQuery").Addr(), 1, uintptr(query), 0, 0)
-		return r0
-	}
-
-	var q windows.Handle
-	name, err := windows.UTF16PtrFromString("no_such_source")
-	if err != nil {
-		t.Fatal(err)
-	}
-	errno := pdhOpenQuery(name, 0, &q)
-	if errno == 0 {
-		pdhCloseQuery(q)
-		t.Fatal("PdhOpenQuery succeeded, but expected to fail.")
-	}
+	dll := windows.MustLoadDLL("netevent.dll")
 
+	const TITLE_SC_MESSAGE_BOX uint32 = 0xC0001B75
 	const flags uint32 = syscall.FORMAT_MESSAGE_FROM_HMODULE | syscall.FORMAT_MESSAGE_ARGUMENT_ARRAY | syscall.FORMAT_MESSAGE_IGNORE_INSERTS
 	buf := make([]uint16, 300)
-	_, err = windows.FormatMessage(flags, uintptr(dll.Handle), uint32(errno), 0, buf, nil)
+	_, err := windows.FormatMessage(flags, uintptr(dll.Handle), TITLE_SC_MESSAGE_BOX, 0, buf, nil)
 	if err != nil {
-		t.Fatalf("FormatMessage for handle=%x and errno=%x failed: %v", dll.Handle, errno, err)
+		t.Fatalf("FormatMessage for handle=%x and errno=%x failed: %v", dll.Handle, TITLE_SC_MESSAGE_BOX, err)
 	}
 }