/usr/lib/libmpi_cxx.so.1 is in libopenmpi1.6 1.6.5-9.1+deb8u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libmpi_cxx.so.1.0.2
/usr/lib/libmpi_cxx.so.1.0.2