Fix another syntax error

scripts/start_server

@@ -25,6 +25,6 @@ if [ -n "${use_tcpdump}" ]; then
   ./tcpdump -c $nb_packets -i eth0 -w tmp.pcap -tt --time-stamp-precision=nano udp port 50000;
   ./tshark -r tmp.pcap --disable-protocol dcp-etsi --disable-protocol dcp-pft -t e -E separator=, -T fields -e frame.number -e frame.time_epoch -e data.data > tmp.out;
   ./txtime_stats.py -f tmp.out;
-else then
+else
   ../packet-exchange/build/server_arm -a -p 99;
 fi