docker: fix Valgrind errors on Xenial by updating to v3.12.0 The Valgrind version shipped with Xenial has some bugs that keep our tests from working due to bad interactions with openssl [1]. Fix this by using the "hola-launchpad/valgrind" PPA that provides a newer version for which the bug has been fixed. [1]: https://bugs.launchpad.net/ubuntu/+source/valgrind/+bug/1574437
diff --git a/azure-pipelines/docker/xenial b/azure-pipelines/docker/xenial
index deded54..67a27e4 100644
--- a/azure-pipelines/docker/xenial
+++ b/azure-pipelines/docker/xenial
@@ -1,6 +1,8 @@
ARG BASE
FROM $BASE
-RUN apt-get update && \
+RUN echo 'deb http://ppa.launchpad.net/hola-launchpad/valgrind/ubuntu xenial main' >/etc/apt/sources.list.d/valgrind.list && \
+ apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 8A0303A7544D59A08EBD1D621BCFD9273D292CF6 && \
+ apt-get update && \
apt-get install -y --no-install-recommends \
clang \
cmake \