Multiply 1996-alloc_dnsbuf-crash-test.pkt by 300000 via TCP

The test for assertion failure via large TCP packet needs to be repeated
multiple times (we use 300000).  This commit fixes the input file to be
properly hexlified and uses the new packet.pl -r feature to send it
300000 times via TCP.

(cherry picked from commit 5f6eb014aa)

bin/tests/system/tcp/1996-alloc_dnsbuf-crash-test.pkt

@@ -0,0 +1,12 @@
+# Transaction ID
+0001
+# Standard query
+0000
+# Questions: 1, Additional: 1
+0001 0000 0000 0000
+# QNAME: www.isc.org
+03 697363 03 6F7267 00
+# Type: AXFR
+00fc
+# Class: IN
+0001

bin/tests/system/tcp/tests.sh

@@ -187,7 +187,7 @@ status=$((status + ret))
 n=$((n + 1))
 echo_i "checking that BIND 9 doesn't crash on long TCP messages ($n)"
 ret=0
-$PERL ../packet.pl -a "10.53.0.1" -p "${PORT}" -t udp 1996-alloc_dnsbuf-crash-test.pkt || ret=1
+$PERL ../packet.pl -a "10.53.0.1" -p "${PORT}" -t tcp -r 300000 1996-alloc_dnsbuf-crash-test.pkt || ret=1
 dig_with_opts +tcp @10.53.0.1 txt.example > dig.out.test$n || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=$((status + ret))