/usr/share/doc/gnat-6-sjlj-arm-linux-gnueabi is in gnat-6-sjlj-arm-linux-gnueabi 6.3.0-18cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gcc-6-arm-linux-gnueabi-base
/usr/share/doc/gcc-6-arm-linux-gnueabi-base