Enable set -x for ipv6 lab scripts

It's more clear this way what the script does, and where it fails (if it
fails).

Author: Ihar Hrachyshka

devsetup/scripts/ipv6-nat64/nat64_router.sh

@@ -14,7 +14,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-set -e
+set -ex
 
 if [ "$EUID" -eq 0 ]; then
     echo "Please do not run as root."

devsetup/scripts/ipv6-nat64/network.sh

@@ -14,7 +14,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-set -e
+set -ex
 
 if [ "$EUID" -eq 0 ]; then
     echo "Please do not run as root."

devsetup/scripts/ipv6-nat64/sno.sh

@@ -14,7 +14,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-set -e
+set -ex
 
 if [ "$EUID" -eq 0 ]; then
     echo "Please do not run as root."