/usr/lib/mpich-mpd/include/mpi2c++/ is in libmpich-mpd1.0-dev 1.2.7-10ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/mpich-mpd/include/mpi2c++/comm.h
/usr/lib/mpich-mpd/include/mpi2c++/comm_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/constants.h
/usr/lib/mpich-mpd/include/mpi2c++/datatype.h
/usr/lib/mpich-mpd/include/mpi2c++/datatype_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/errhandler.h
/usr/lib/mpich-mpd/include/mpi2c++/errhandler_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/exception.h
/usr/lib/mpich-mpd/include/mpi2c++/functions.h
/usr/lib/mpich-mpd/include/mpi2c++/functions_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/group.h
/usr/lib/mpich-mpd/include/mpi2c++/group_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/intercomm.h
/usr/lib/mpich-mpd/include/mpi2c++/intercomm_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/intracomm.h
/usr/lib/mpich-mpd/include/mpi2c++/intracomm_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/mpi++.h
/usr/lib/mpich-mpd/include/mpi2c++/mpi2c++_config.h
/usr/lib/mpich-mpd/include/mpi2c++/mpi2c++_list.h
/usr/lib/mpich-mpd/include/mpi2c++/mpi2c++_map.h
/usr/lib/mpich-mpd/include/mpi2c++/op.h
/usr/lib/mpich-mpd/include/mpi2c++/op_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/pcomm.h
/usr/lib/mpich-mpd/include/mpi2c++/pdatatype.h
/usr/lib/mpich-mpd/include/mpi2c++/perrhandler.h
/usr/lib/mpich-mpd/include/mpi2c++/pexception.h
/usr/lib/mpich-mpd/include/mpi2c++/pgroup.h
/usr/lib/mpich-mpd/include/mpi2c++/pgroup_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/pintercomm.h
/usr/lib/mpich-mpd/include/mpi2c++/pintracomm.h
/usr/lib/mpich-mpd/include/mpi2c++/pmpi++.h
/usr/lib/mpich-mpd/include/mpi2c++/pop.h
/usr/lib/mpich-mpd/include/mpi2c++/pop_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/prequest.h
/usr/lib/mpich-mpd/include/mpi2c++/prequest_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/pstatus.h
/usr/lib/mpich-mpd/include/mpi2c++/pstatus_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/ptopology.h
/usr/lib/mpich-mpd/include/mpi2c++/request.h
/usr/lib/mpich-mpd/include/mpi2c++/request_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/status.h
/usr/lib/mpich-mpd/include/mpi2c++/status_inln.h
/usr/lib/mpich-mpd/include/mpi2c++/topology.h
/usr/lib/mpich-mpd/include/mpi2c++/topology_inln.h