portage-utils: Backport to fix ewarn PMS issues

Backport the upstream fix from:
https://github.com/gentoo/portage-utils/pull/23

This resolves issues with ebuilds/eclasses that might process the stdout
of utility functions that use ewarn() and similar, not expecting the
ewarn message to be dumped to stdout.

BUG=b:280432913
TEST=CQ

Change-Id: If120982322944a9bbf7931badc83c56c12b1d206
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/5370656
Auto-Submit: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
3 files changed