dhcpcd: Emit more state change events

Send more state change signals over the D-Bus interface.
This will allow shill to gather metrics on the dhcp client
behavior, including recent changes regarding NAK behavior.

BUG=chromium:384897
TEST=DHCP autotests, and instrumentation inside shill

Change-Id: Ifc596dde5b099327ec33a7b3ea728a75e33f1e9d
Reviewed-on: https://chromium-review.googlesource.com/208835
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
2 files changed