/usr/lib/gcc-cross/mips64-linux-gnuabi64/7.3.0 is in gcc-7-mips64-linux-gnuabi64-base 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/mips64-linux-gnuabi64/7
/usr/lib/gcc-cross/mips64-linux-gnuabi64/7