peerd: Use optional port in mDNS advertisements

BUG=chromium:425542
TEST=unittests, modified integration tests

Change-Id: I76371a6a92e4a60df1793b29f789796b412830f9
Reviewed-on: https://chromium-review.googlesource.com/228301
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
Tested-by: Christopher Wiley <wiley@chromium.org>
2 files changed