/usr/lib/gcc-cross/powerpc-linux-gnu/6.4.0 is in gcc-6-powerpc-linux-gnu-base 6.4.0-17ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/powerpc-linux-gnu/6
/usr/lib/gcc-cross/powerpc-linux-gnu/6