cryptography: upgraded package to upstream

Upgraded dev-python/cryptography to version 2.8-r1 on amd64

BUG=chromium:1069880
TEST=Full unittest suite. Python change so should not have
any board-specific dependencies.

Change-Id: I8959953a2eca10f5282c1bbc44654fb20cb63219
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2149274
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Bob Brandt <brndt@google.com>
Auto-Submit: Bob Brandt <brndt@google.com>
Commit-Queue: Bob Brandt <brndt@google.com>
7 files changed