libxml2, libxslt: upgraded packages to upstream

Upgraded dev-libs/libxml2 to version 2.9.10 on amd64
Upgraded dev-libs/libxslt to version 1.1.34 on amd64

BUG=b/146263250 b/147168856
TEST=Presubmit
RELEASE_NOTE=Fixed CVE-2019-5815 and CVE-2019-19956

Upstream commit id: 8be413f4cfef7b1e58feb23ac0535c16cba7edfb

Change-Id: I1517bf7f9ce796523460453af16b8ef32fe0d9bc
15 files changed