/usr/include/google/protobuf-c/protobuf-c.h is in libprotobuf-c-dev 1.2.1-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/google/protobuf-c/../../protobuf-c/protobuf-c.h
/usr/include/google/protobuf-c/../../protobuf-c/protobuf-c.h