/usr/lib/libGraphicsMagick++.so is in libgraphicsmagick++1-dev 1.3.12-1.1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libGraphicsMagick++.so.3.3.0
/usr/lib/libGraphicsMagick++.so.3.3.0