Smarter filter when children won't match

This improves restore performance by several orders of magniture by not
going through the whole tree recursively when we can anticipate that no
match will ever occur.

cmd/restic/cmd_backup.go

@@ -417,7 +417,7 @@ func runBackup(opts BackupOptions, gopts GlobalOptions, args []string) error {
 	}
 
 	selectFilter := func(item string, fi os.FileInfo) bool {
-		matched, err := filter.List(opts.Excludes, item)
+		matched, _, err := filter.List(opts.Excludes, item)
 		if err != nil {
 			Warnf("error for exclude pattern: %v", err)
 		}

cmd/restic/cmd_restore.go

@@ -113,22 +113,22 @@ func runRestore(opts RestoreOptions, gopts GlobalOptions, args []string) error {
 		return nil
 	}
 
-	selectExcludeFilter := func(item string, dstpath string, node *restic.Node) bool {
-		matched, err := filter.List(opts.Exclude, item)
+	selectExcludeFilter := func(item string, dstpath string, node *restic.Node) (bool, bool) {
+		matched, childMayMatch, err := filter.List(opts.Exclude, item)
 		if err != nil {
 			Warnf("error for exclude pattern: %v", err)
 		}
 
-		return !matched
+		return !matched, childMayMatch
 	}
 
-	selectIncludeFilter := func(item string, dstpath string, node *restic.Node) bool {
-		matched, err := filter.List(opts.Include, item)
+	selectIncludeFilter := func(item string, dstpath string, node *restic.Node) (bool, bool) {
+		matched, childMayMatch, err := filter.List(opts.Include, item)
 		if err != nil {
 			Warnf("error for include pattern: %v", err)
 		}
 
-		return matched
+		return matched, childMayMatch
 	}
 
 	if len(opts.Exclude) > 0 {