[PATCH] Add DBus RPC support

Cherry-picked from
https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/
master/net-misc/dhcpcd/files/patches/dhcpcd-6.8.2-Add-DBus-RPC-support.patch.

Porting the DBus support from version 5.1.4 and allow it to be
configurable through the package configuration. Removed the unused
and incomplete implemention for DBus method GetInterfaces and GetStatus.

Also: update the default lease file name to tailor around the
expectation of shill ("dhcpcd-%dev.lease).

Also: update the config file to meet shill's expectation.

BUG: 22956197
Change-Id: Ic729dffc6b14fed0b27ed0731c11ef609434e03c

Review URL: http://codereview.chromium.org/2428004
Review URL: http://codereview.chromium.org/2851022
Review URL: http://codereview.chromium.org/2851023
Review URL: http://codereview.chromium.org/2865017
Review URL: http://codereview.chromium.org/2965010
Review URL: http://codereview.chromium.org/2957010
Review URL: http://codereview.chromium.org/3060016
Reviewed-on: http://gerrit.chromium.org/gerrit/2228
Reviewed-on: https://gerrit.chromium.org/gerrit/22597
Reviewed-on: https://gerrit.chromium.org/gerrit/36716
Reviewed-on: https://gerrit.chromium.org/gerrit/38183
Reviewed-on: https://gerrit.chromium.org/gerrit/59967
Reviewed-on: https://chromium-review.googlesource.com/178462
Reviewed-on: https://chromium-review.googlesource.com/185086
Reviewed-on: https://chromium-review.googlesource.com/195269
Reviewed-on: https://chromium-review.googlesource.com/259072
16 files changed