Fix #5231: "make html" does not read and build "po" files in "locale" dir

CHANGES

@@ -26,6 +26,7 @@ Bugs fixed
 * C++, parse unary right fold expressions and binary fold expressions.
 * pycode could not handle egg files on windows
 * #5928: KeyError: 'DOCUTILSCONFIG' when running build
+* #5231: "make html" does not read and build "po" files in "locale" dir
 
 Testing
 --------

sphinx/util/matching.py

@@ -11,6 +11,8 @@
 
 import re
 
+from sphinx.util.osutil import canon_path
+
 if False:
     # For type annotation
     from typing import Callable, Dict, List, Match, Pattern  # NOQA
@@ -86,6 +88,7 @@ class Matcher(object):
 
     def match(self, string):
         # type: (unicode) -> bool
+        string = canon_path(string)
         return any(pat(string) for pat in self.patterns)