libxml2: upgraded package to upstream

Upgraded dev-libs/libxml2 to version 2.9.2 for security fixes

BUG=chromium:431158
TEST=cbuildbot chromiumos-sdk --local

Change-Id: I83ce612d860ca90a54beead12d0cff71d0b21d29
Reviewed-on: https://chromium-review.googlesource.com/251232
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Utkarsh Sanghi <usanghi@chromium.org>
Tested-by: Utkarsh Sanghi <usanghi@chromium.org>
15 files changed