fix build for windows

found with "make buildall", it was broken since the change for reusable components.

moxio/syncdir_windows.go

@@ -1,8 +1,12 @@
 package moxio
 
+import (
+	"github.com/mjl-/mox/mlog"
+)
+
 // SyncDir opens a directory and syncs its contents to disk.
 // SyncDir is a no-op on Windows.
-func SyncDir(dir string) error {
+func SyncDir(log mlog.Log, dir string) error {
 	// todo: how to sync a directory on windows?
 	return nil
 }