Pull request: use mathutil

Merge in DNS/adguard-home from use-mathutil to master

Squashed commit of the following:

commit cfe2c02a7bb727e81fcd91674aa777df37413a8e
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Jan 24 18:12:32 2023 +0300

    all: use mathutil

internal/filtering/rewrites.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 
 	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/mathutil"
 	"github.com/miekg/dns"
 	"golang.org/x/exp/slices"
 )
@@ -201,7 +202,7 @@ func findRewrites(
 		if isWildcard(r.Domain) {
 			// Don't use rewrites[:0], because we need to return at least one
 			// item here.
-			rewrites = rewrites[:max(1, i)]
+			rewrites = rewrites[:mathutil.Max(1, i)]
 
 			break
 		}
@@ -209,11 +210,3 @@ func findRewrites(
 
 	return rewrites, matched
 }
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-
-	return b
-}