Merge in DNS/adguard-home from 2276-fix-portability to master Updates #2276. Squashed commit of the following: commit 3019099f2498923495575873daf372598aa72478 Author: Ainar Garipov <A.Garipov@AdGuard.COM> Date: Thu Dec 31 14:31:02 2020 +0300 scripts: don't use features not guaranteed by posix