libffi: upgraded package to upstream

Upgraded dev-libs/libffi to version 3.1-r3 as newer aarch64 wants it.

BUG=None
TEST=`cbuildbot chromiumos-sdk` passes
TEST=`cbuildbot {x86-alex,lumpy,daisy}-release` passes
TEST=`emerge-arm64-generic libffi` works

Change-Id: I2b3914dacc9bef3d37afac4745ffdc4c1b4e842c
Reviewed-on: https://chromium-review.googlesource.com/219085
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
9 files changed