sd-journal: drop unused function prototype

Follow-up for 8b4fbbb0a1.

The function was renamed and moved by
035b0f8fe8.
Maybe the prototype is mistakenly re-introduced on rebase.

src/libsystemd/sd-journal/journal-file.h

@@ -310,7 +310,6 @@ void journal_file_print_header(JournalFile *f);
 
 int journal_file_archive(JournalFile *f, char **ret_previous_path);
 int journal_file_parse_uid_from_filename(const char *path, uid_t *uid);
-JournalFile* journal_initiate_close(JournalFile *f, Set *deferred_closes);
 
 int journal_file_dispose(int dir_fd, const char *fname);