[r21880]GrampsLocale: Better handling of unset $LANG or $LANG == 'C'

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@21883 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
[r21881]GrampsLocale: Ensure posix collation and calendar

are set correctly

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@21884 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
[r21882]GrampsLocale: Improve windows handling of no locale

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@21885 4ae1f11a-8b86-4847-b8af-ab372f36d1fd