ttcn3-tcpdump-start.sh: Don't call tcpdump log files ".log"

The problem is that we use ttcn3_logmerge FOO_Tests.*.log and that the
tcpdump stdout log files also match this pattern.  Call them
.pcap.stdout in order to avoid them falling into the globbing pattern of
the TITAN log files.

Change-Id: Iac1ae217b006182121d86375ffa4d3c00ef37e8b

ttcn3-tcpdump-start.sh

@@ -20,7 +20,7 @@ if [ "$(id -u)" = "0" ]; then
 else
 	CMD="sudo $TCPDUMP"
 fi
-$CMD -U -s 0 -n -i any -w "$TTCN3_PCAP_PATH/$TESTCASE.pcap" >$TTCN3_PCAP_PATH/$TESTCASE.pcap.log 2>&1 &
+$CMD -U -s 0 -n -i any -w "$TTCN3_PCAP_PATH/$TESTCASE.pcap" >$TTCN3_PCAP_PATH/$TESTCASE.pcap.stdout 2>&1 &
 PID=$!
 echo $PID > $PIDFILE