Pull request: home: rm unnecessary locking in update; refactor

Merge in DNS/adguard-home from 4499-rm-unnecessary-locking to master

Squashed commit of the following:

commit 6d70472506dd0fd69225454c73d9f7f6a208b76b
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Apr 25 17:26:54 2022 +0300

    home: rm unnecessary locking in update; refactor

internal/aghnet/net_bsd.go

@@ -1,5 +1,5 @@
-//go:build !linux
-// +build !linux
+//go:build darwin || freebsd || openbsd
+// +build darwin freebsd openbsd
 
 package aghnet
 

internal/aghnet/net_windows.go

@@ -1,5 +1,5 @@
-//go:build !(linux || darwin || freebsd || openbsd)
-// +build !linux,!darwin,!freebsd,!openbsd
+//go:build windows
+// +build windows
 
 package aghnet
 
@@ -13,6 +13,10 @@ import (
 	"golang.org/x/sys/windows"
 )
 
+func canBindPrivilegedPorts() (can bool, err error) {
+	return true, nil
+}
+
 func ifaceHasStaticIP(string) (ok bool, err error) {
 	return false, aghos.Unsupported("checking static ip")
 }