/usr/lib/x86_64-linux-gnu/libgazebo.so is in libgazebo7-dev 7.0.0+dfsg-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgazebo.so.7
/usr/lib/x86_64-linux-gnu/libgazebo.so.7