/usr/lib/gcc-cross/mips-linux-gnu/8/plugin/libcp1plugin.so is in gcc-8-mips-linux-gnu 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/mips-linux-gnu/8/plugin/libcp1plugin.so.0.0.0