StaticFileSet: Fix os.walk for utf8_mode

Bug: https://bugs.gentoo.org/916182
Signed-off-by: Zac Medico <zmedico@gentoo.org>

lib/portage/_sets/files.py

@@ -1,10 +1,11 @@
-# Copyright 2007-2020 Gentoo Authors
+# Copyright 2007-2023 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 import errno
 import re
 from itertools import chain
 
+import portage
 from portage import os
 from portage import _encodings
 from portage import _unicode_decode
@@ -176,6 +177,11 @@ def multiBuilder(self, options, settings, trees):
             directory = normalize_path(directory)
 
             for parent, dirs, files in os.walk(directory):
+                if portage.utf8_mode:
+                    parent = os.fsencode(parent)
+                    dirs = [os.fsencode(value) for value in dirs]
+                    files = [os.fsencode(value) for value in files]
+
                 try:
                     parent = _unicode_decode(
                         parent, encoding=_encodings["fs"], errors="strict"