/usr/lib/gcc-cross/powerpc-linux-gnuspe/5/libobjc_gc.so is in libobjc-5-dev-powerpcspe-cross 5.3.1-14ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/powerpc-linux-gnuspe/5/../../../../powerpc-linux-gnuspe/lib/libobjc_gc.so.4