/usr/lib/gcc-cross/mips64-linux-gnuabi64/6/liblto_plugin.so is in cpp-6-mips64-linux-gnuabi64 6.3.0-18cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/mips64-linux-gnuabi64/6/liblto_plugin.so.0.0.0