vendor: Export cloe/vtd-conan-package Docker image with Ubuntu 18:04

Otherwise it's almost impossible to extract the data out, due to
limitations in Docker.

Author: cassava

vendor/vtd/Dockerfile

@@ -155,5 +155,5 @@ RUN conan create conanfile.py ${PACKAGE_FQN} && \
     conan remove -b -s -f vtd && \
     find /root/.conan/data -type d -name "dl" -exec rm -rf {} +
 
-FROM scratch
+FROM ubuntu:18.04
 COPY --from=build /root/.conan/data/vtd /vtd