THRIFT-4106: fix errors concurrency_test was identifying
Client: C++

This closes #1343
diff --git a/build/docker/ubuntu-xenial/Dockerfile b/build/docker/ubuntu-xenial/Dockerfile
index 6bad6a9..6324ec2 100644
--- a/build/docker/ubuntu-xenial/Dockerfile
+++ b/build/docker/ubuntu-xenial/Dockerfile
@@ -60,6 +60,7 @@
       llvm \
       ninja-build \
       pkg-config \
+      valgrind \
       vim
 ENV PATH /usr/lib/llvm-3.8/bin:$PATH