trx_undo_page_report_rename(): Use the correct maximum length of
a table name. Both the database name and the table name can be up to
NAME_CHAR_LEN (64 characters) times 5 bytes per character in the
my_charset_filename encoding. They are not encoded in UTF-8!

fil_op_write_log(): Reserve the correct amount of log buffer for
a rename operation. The file name will be appended by
mlog_catenate_string().

rename_file_ext(): Reserve a large enough buffer for the file names.