message: Try to ensure that stddef.h is present
diff: @@ -3,7 +3,7 @@ LABEL maintainer="Martin Thomson <mt@lowentropy.net>"
  RUN apt-get update && apt-get install -y --no-install-recommends \
  ca-certificates coreutils curl git make mercurial ssh \
  - build-essential gyp ninja-build pkg-config zlib1g-dev \
  + build-essential libc6-dev libc++-dev gyp ninja-build pkg-config zlib1g-dev \
  libclang1 \
  && apt-get autoremove -y && apt-get clean -y \
  && rm -rf /var/lib/apt/lists/*
  