ipn/conffile: don't depend on hujson on iOS/Android

Fixes #13772

Change-Id: I3ae03a5ee48c801f2e5ea12d1e54681df25d4604
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/conffile/conffile_hujson.go

@@ -0,0 +1,20 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !ios && !android
+
+package conffile
+
+import "github.com/tailscale/hujson"
+
+// Only link the hujson package on platforms that use it, to reduce binary size
+// & memory a bit.
+//
+// (iOS and Android don't have config files)
+
+// While the linker's deadcode mostly handles the hujson package today, this
+// keeps us honest for the future.
+
+func init() {
+	hujsonStandardize = hujson.Standardize
+}