/usr/i686-linux-gnu/lib64/libmpx.so.2 is in lib64mpx2-i386-cross 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/i686-linux-gnu/lib64/libmpx.so.2.0.1
/usr/i686-linux-gnu/lib64/libmpx.so.2.0.1