MacLocale: Extract function _mac_get_gramps_defaults

And correct line handling on the languages list.

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21635 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
GrampsLocale: Better handle invalid/missing locale

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21636 4ae1f11a-8b86-4847-b8af-ab372f36d1fd