/usr/include/mpich2/ is in libmpich2-dev 1.4.1-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mpich2/mpi.h
/usr/include/mpich2/mpi.mod
/usr/include/mpich2/mpi_base.mod
/usr/include/mpich2/mpi_constants.mod
/usr/include/mpich2/mpi_sizeofs.mod
/usr/include/mpich2/mpicxx.h
/usr/include/mpich2/mpif.h
/usr/include/mpich2/mpio.h
/usr/include/mpich2/mpiof.h
/usr/include/mpich2/mpix.h
/usr/include/mpich2/opa_config.h
/usr/include/mpich2/opa_primitives.h
/usr/include/mpich2/opa_queue.h
/usr/include/mpich2/opa_util.h
/usr/include/mpich2/primitives/
/usr/include/mpich2/primitives/opa_by_lock.h
/usr/include/mpich2/primitives/opa_emulated.h
/usr/include/mpich2/primitives/opa_gcc_ia64.h
/usr/include/mpich2/primitives/opa_gcc_intel_32_64.h
/usr/include/mpich2/primitives/opa_gcc_intel_32_64_barrier.h
/usr/include/mpich2/primitives/opa_gcc_intel_32_64_ops.h
/usr/include/mpich2/primitives/opa_gcc_intel_32_64_p3.h
/usr/include/mpich2/primitives/opa_gcc_intel_32_64_p3barrier.h
/usr/include/mpich2/primitives/opa_gcc_intrinsics.h
/usr/include/mpich2/primitives/opa_gcc_ppc.h
/usr/include/mpich2/primitives/opa_gcc_sicortex.h
/usr/include/mpich2/primitives/opa_nt_intrinsics.h
/usr/include/mpich2/primitives/opa_sun_atomic_ops.h
/usr/include/mpich2/primitives/opa_unsafe.h