Add eight time test files with packet dates in 2038, 2039, 2106 and 2107

Add eight time test files with packet dates in 2038, 2039, 2106 and 2107

Each capture file contains one packet.

time_2038.pcap:		   2038-01-01 00:00:00
time_2038_max.pcap:	   2038-01-19 03:14:07
time_2038_overflow.pcap:   2038-01-19 03:14:08
time_2039.pcap:		   2039-01-01 00:00:00
time_2106.pcap:		   2106-01-01 00:00:00
time_2106_max.pcap:	   2106-02-07 06:28:15
time_2106_overflow.pcapng: 2106-02-07 06:28:16
time_2107.pcapng:	   2107-01-01 00:00:00

The packet time when > 2038-01-19T03:14:07Z cannot be correctly printed
if time_t size is 32 bits (overflow).
Some tests are run only if HAVE_TIME_T_64 is set. it depends on the
output of "./tcpdump --time-t-size" (32 or 64).

A 32-bit unsigned time_t goes until 2106-02-07T06:28:15Z.
All values above require a pcapng file.