unifdef: upgraded package to upstream

Upgraded dev-util/unifdef to version 2.12 on amd64, arm.
Please note dev-util/unifdef is not available on arm64.

BUG=b:218560801
TEST=FEATURES=test emerge-drallion dev-util/unifdef

Change-Id: I3addc675bd74667cf1b5fea268ca6b297f21d686
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3448051
Tested-by: Henry Yang <yanghenry@google.com>
Reviewed-by: Michael Pishchagin <mblsha@google.com>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Commit-Queue: Gwendal Grignou <gwendal@chromium.org>
5 files changed