ping tests: Add a regression test

[jlduran_gmail.com]

Summary

Test regression fixed in 4630a3252ac8ad2f5acddf0d1efb26795cb3190b.
Add two tests that do not use the verbose flag, so the code path in question can be reached:

1. Respond with a proper ICMP destination host unreachable packet.
2. Respond with a doctored ICMP destination host unreachable packet, that has the ICMP Identifier field modified (+1 bit).

Test Plan

kyua test -k /usr/tests/Kyuafile sbin/ping/ping_test
kyua test -k /usr/tests/Kyuafile sbin/ping/test_ping.py

Without the code that was accidentally removed, test 1 should fail.

[cy]

sbin/ping/tests/test_ping.py

1234

Minor nit: git apply complains about trailing space here.

[cy]

sbin/ping/tests/test_ping.py

1234

slippy$ git apply /tmp/D39244.diff
/tmp/D39244.diff:71: trailing whitespace.
4 5 00 0054 0001 0 0000 40 01 f6a4 192.0.2.1 192.0.2.2
warning: 1 line adds whitespace errors.
slippy$

[jlduran_gmail.com]

sbin/ping/tests/test_ping.py

1234

The trailing space is needed, otherwise the test will fail. I have a number of cosmetic changes planned for ping, which remove the trailing space, among other fixes.

[cy]

I'm happy with it.