[i18n][man] add missing deunicode().

We get the following error message when we have a translated admonition
(e.g. 'note') label:

  Exception occurred:
      File "../sphinx/sphinx/locale/__init__.py", line 75, in __str__
        return str(self.data)
        UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-2: ordinal not in range(128)

sphinx/writers/manpage.py

@@ -197,7 +197,7 @@ class ManualPageTranslator(BaseTranslator):
     def visit_admonition(self, node, name=None):
         if name:
             self.body.append('.IP %s\n' %
-                             admonitionlabels.get(name, name))
+                             self.deunicode(admonitionlabels.get(name, name)))
 
     def visit_productionlist(self, node):
         self.ensure_eol()