wmaker: update error message to have only one string to be translated

As a previous patch modified some instances of the error message to include
more information to the user, it is a good idea to update also the other
uses of the message, so that:
 - people helping on translation will have less messages to translate
 - this mean we provide more information to the user in these places too,
which can help him solve the problem

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>
Signed-off-by: Carlos R. Mafra <crmafra@gmail.com>

po/zh_TW.po

@@ -1205,8 +1205,8 @@ msgstr "%s: 無法開啟/預先處理選單檔"
 
 #: ../src/rootmenu.c:1217 ../src/rootmenu.c:1321
 #, c-format
-msgid "%s:could not open menu file"
-msgstr "%s: 無法開啟選單檔"
+msgid "could not open menu file \"%s\": %s"
+msgstr "無法開啟選單檔 \"%s\": %s"
 
 #: ../src/rootmenu.c:1244
 #, c-format