autotest: dhcp: Add test for non-ASCII string parameters

Pass a DHCP server parameter that has non-ASCII data in it.
This is known to crash our dhcpcd implementation.

BUG=chromium-os:35756
TEST=Run test before and after fix to dhcpcd

Change-Id: Icd171880e61462be07b3d40a217a378419b95184
Reviewed-on: https://gerrit.chromium.org/gerrit/36714
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Ready: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
5 files changed