/usr/lib/gcc-cross/powerpc-linux-gnu/5/64/libobjc.so is in lib64objc-5-dev-powerpc-cross 5.5.0-12ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/powerpc-linux-gnu/5/64/../../../../../powerpc-linux-gnu/lib64/libobjc.so.4