/usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 is in libx11-xcb1 2:1.6.4-3+deb9u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1.0.0
/usr/lib/x86_64-linux-gnu/libX11-xcb.so.1.0.0