/usr/include/XmlRpcCpp.h is in libxmlrpc-core-c3-dev 1.16.33-3.1ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/xmlrpc-c/oldcppwrapper.hpp
/usr/include/xmlrpc-c/oldcppwrapper.hpp