/usr/lib/clang/4.0/include is in libclang-common-4.0-dev 1:4.0.1-10~deb9u2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/clang/4.0/../../llvm-4.0/lib/clang/4.0.1/include
/usr/lib/clang/4.0/../../llvm-4.0/lib/clang/4.0.1/include