Adding a Dockerfile script that can build a docker image with an msan-compatible C++ compiler.

tools/dockerfile/msan_cxx/Dockerfile

+FROM ubuntu:latest
+
+RUN apt-get update && apt-get install -y \
+  cmake \
+  g++ \
+  gcc \
+  git \
+  make \
+  python \
+  && apt-get clean
+
+RUN git clone -b release_36 http://llvm.org/git/llvm.git
+RUN git clone -b release_36 http://llvm.org/git/clang.git
+RUN git clone -b release_36 http://llvm.org/git/compiler-rt.git
+RUN git clone -b release_36 http://llvm.org/git/clang-tools-extra.git
+RUN git clone -b release_36 http://llvm.org/git/libcxx.git
+RUN git clone -b release_36 http://llvm.org/git/libcxxabi.git
+
+RUN mv clang llvm/tools
+RUN mv compiler-rt llvm/projects
+RUN mv clang-tools-extra llvm/tools/clang/tools
+RUN mv libcxx llvm/projects
+RUN mv libcxxabi llvm/projects
+
+RUN mkdir llvm-build
+RUN cd llvm-build && cmake ../llvm
+RUN make -C llvm-build && make -C llvm-build install && rm -rf llvm-build
+
+CMD ["bash"]