This commit also provides the correct month names in both nominative
and genitive case for Silesian language, as required by the fix for
the bug 10871.
[BZ #24652]
* localedata/locales/szl_PL (abday): Spelling corrections.
(day): Likewise.
(abmon): Likewise.
(mon): Rename to...
(alt_mon): This, then apply spelling corrections.
(mon): New entry, month names in the genitive case.