Add stretch-clang8 dockerfile

Author: Yevgeny Pats

docker/debian/stretch/clang8/Dockerfile

@@ -0,0 +1,7 @@
+FROM docker.pkg.github.com/fuzzitdev/fuzzit/debian-llvm8:latest
+
+LABEL maintainer="Fuzzit.dev, inc."
+
+RUN apt-get -qqy update && apt-get install -y git clang-8 libclang-common-8-dev libclang-8-dev libclang1-8 clang-format-8 cmake
+
+WORKDIR /app