/usr/lib/gcc-cross/aarch64-linux-gnu/5.4.0 is in gcc-5-aarch64-linux-gnu-base 5.4.0-6ubuntu1~16.04.9cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/aarch64-linux-gnu/5
/usr/lib/gcc-cross/aarch64-linux-gnu/5