apache_log_metrics.py: Fix "ip_addr" group match

A bug was introduced by switching to named regex match groups - the
ip_addr group was referenced as "ipaddr".

BUG=chromium:630776
TEST=added a unit test.

Change-Id: I6a51c2c18aeffc2fbda53446c5e5690ae53060cc
Reviewed-on: https://chromium-review.googlesource.com/362588
Reviewed-by: Richard Barnette <jrbarnette@google.com>
Tested-by: Paul Hobbs <phobbs@google.com>
2 files changed