/usr/lib/gcc-cross/powerpc64le-linux-gnu/6/libitm.so is in libgcc-6-dev-ppc64el-cross 6.3.0-18cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/powerpc64le-linux-gnu/6/../../../../powerpc64le-linux-gnu/lib/libitm.so.1