Pull request: replace agherr with golibs' errors

Merge in DNS/adguard-home from golibs-errors to master

Squashed commit of the following:

commit 5aba278a31c5a213bd9e08273ce7277c57713b22
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon May 24 17:05:18 2021 +0300

    all: imp code

commit f447eb875b81779fa9e391d98c31c1eeba7ef323
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon May 24 15:33:45 2021 +0300

    replace agherr with golibs' errors

internal/querylog/search.go

@@ -142,7 +142,12 @@ func (l *queryLog) searchFiles(
 
 		return entries, oldest, 0
 	}
-	defer r.Close()
+	defer func() {
+		derr := r.Close()
+		if derr != nil {
+			log.Error("querylog: closing file: %s", err)
+		}
+	}()
 
 	if params.olderThan.IsZero() {
 		err = r.SeekStart()