sys-apps/grep: upgraded package to upstream 2.20

Upgraded sys-apps/grep to version 2.20 on amd64, arm, x86

BUG=chromium:406221
TEST=cbuildbot chromiumos-sdk mipsel-o32-generic

Change-Id: I1f2f5696f59536e02fd21037f6d8cfe2595aa540
Reviewed-on: https://chromium-review.googlesource.com/213742
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
7 files changed