log time in tcpdump-start and -stop.sh

Also log the testcase name in tcpdump-start.sh.

The output now looks like

    ------ MSC_Tests.TC_mo_cc_bssmap_clear ------
    Thu Mar  7 13:21:00 UTC 2019
    [...]
    Thu Mar  7 13:21:04 UTC 2019
    ====== MSC_Tests.TC_mo_cc_bssmap_clear pass ======

The reason to log start and end dates came up like this: I noticed a segfault
in a tested program at a specific time. From the timestamp I tried to find out
which of the tests saw the failure. (After a segfault, all subsequent tests run
and fail, but it is not obvious which failure occured because of a segfault,
and which ones just normally failed before that.) Looking at the timestamps of
the log files didn't help, because the ttcn3_logmerge touched those after the
tests completed. So the only way is to cat each individual log file and find
the timestamp.

So this adds an overview of the timestamps without needing to open log files.

Change-Id: I0832d9b5df599baad5dec8d3a993481b4286fbb3

ttcn3-tcpdump-start.sh

@@ -4,6 +4,9 @@ PIDFILE=/tmp/tcpdump.pid
 TCPDUMP=/usr/sbin/tcpdump
 TESTCASE=$1
 
+echo "------ $TESTCASE ------"
+date
+
 if [ "z$TTCN3_PCAP_PATH" = "z" ]; then
 	TTCN3_PCAP_PATH=/tmp
 fi

ttcn3-tcpdump-stop.sh

@@ -4,6 +4,8 @@ PIDFILE=/tmp/tcpdump.pid
 TESTCASE=$1
 VERDICT="$2"
 
+date
+
 if [ x"$VERDICT" = x"pass" ]; then
 	echo "\033[1;32m====== $TESTCASE $VERDICT ======\033[0m"
 else