Introduced time truncation to December 31, 9999 (ticket #1368). Various buffers are allocated in an assumption that there would be no more than 4 year digits. This might not be true on platforms with 64-bit time_t, as 64-bit time_t is able to represent more than that. Such dates with more than 4 year digits hardly make sense though, as various date formats in use do not allow them anyway. As such, all dates are now truncated by ngx_gmtime() to December 31, 9999. This should have no effect on valid dates, though will prevent potential buffer overflows on invalid ones.