ttcn3-tcpdump-start: Fix path of setcap

if we test if /sbin/setcap exists, we als should execute it from that
path, as running from a normal user doesn't have /sbin included in $PATH

Change-Id: I5131f869f86e6d136e0485da5e3749abbfc951e3

ttcn3-tcpdump-start.sh

@@ -39,7 +39,7 @@ if [ -x $DUMPCAP ]; then
     CAP_ERR="1"
     if [ -x /sbin/setcap ]; then
 	# N. B: this check requires libcap2-bin package
-	setcap -q -v 'cap_net_admin,cap_net_raw=pie' $DUMPCAP
+	/sbin/setcap -q -v 'cap_net_admin,cap_net_raw=pie' $DUMPCAP
 	CAP_ERR="$?"
     fi
     if [ -u $DUMPCAP -o "$CAP_ERR" = "0" ]; then