[PATCH] Improve debugability

Cherry-picked from
https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/
master/net-misc/dhcpcd/files/patches/dhcpcd-6.8.2-Improve-debugability.patch.

Increase log level for certain log messages and add more log messages
to improve debugability.

BUG: 22956197
Change-Id: Idec6362a13d946831c8f0837a4cfe31c2671665e

Reviewed-on: https://gerrit.chromium.org/gerrit/42622
Reviewed-on: https://chromium-review.googlesource.com/185511
Reviewed-on: https://chromium-review.googlesource.com/186593
Reviewed-on: https://chromium-review.googlesource.com/206143
Reviewed-on: https://gerrit.chromium.org/gerrit/24835
3 files changed