gplugin/builders

Overhaul convey.yml and add pvs-studio and cleanup the mingw-w64-i686 stuff (still doesn't work)
FROM gplugin/builders:debian-buster-amd64
MAINTAINER Gary Kramlich <grim@reaperworld.com>
RUN set -ex && \
apt-get update && \
apt-get install -y --no-install-recommends clang-tools && \
apt-get clean && \
rm -rf /var/lib/apt/lists
COPY scanbuild/build.sh /