message: [docker] adding clang for validator
  Closes:
  Approved by: bmwill
diff: @@ -4,7 +4,7 @@ FROM debian:stretch as builder
  # docker build --build-arg https_proxy=http://fwdproxy:8080 --build-arg http_proxy=http://fwdproxy:8080
  RUN echo "deb http://deb.debian.org/debian stretch-backports main" > /etc/apt/sources.list.d/backports.list \
  - && apt-get update && apt-get install -y protobuf-compiler/stretch-backports cmake curl \
  + && apt-get update && apt-get install -y protobuf-compiler/stretch-backports cmake curl clang \
  && apt-get clean && rm -r /var/lib/apt/lists/*
  RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain none
  