Pull request: dnsfilter: restore enum value

Merge in DNS/adguard-home from fix-filter-names to master

Squashed commit of the following:

commit 620d80df12878a1b236abb26cd2a331df998a3d5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Dec 14 20:02:41 2020 +0300

    dnsfilter: restore enum value

.githooks/pre-commit

@@ -1,18 +1,13 @@
-#!/bin/bash
-set -e;
+#!/bin/sh
 
-found=0
-git diff --cached --name-only | grep -q '.js$' && found=1
-if [ $found == 1 ]; then
-    npm --prefix client run lint || exit 1
-    npm run test --prefix client || exit 1
+set -e -f -u
+
+if [ "$(git diff --cached --name-only '*.js')" ]
+then
+	make js-lint js-test
 fi
 
-found=0
-git diff --cached --name-only | grep -q '.go$' && found=1
-if [ $found == 1 ]; then
-	make go-lint || exit 1
-	go test ./... || exit 1
+if [ "$(git diff --cached --name-only '*.go')" ]
+then
+	make go-lint go-test
 fi
-
-exit 0;

internal/dnsfilter/dnsfilter.go

@@ -129,6 +129,9 @@ const (
 	NotFilteredNotFound Reason = iota
 	// NotFilteredWhiteList - the host is explicitly whitelisted
 	NotFilteredWhiteList
+	// NotFilteredError is return where there was an error during
+	// checking.  Reserved, currently unused.
+	NotFilteredError
 
 	// reasons for filtering