/usr/lib/x86_64-linux-gnu/libgstreamermm_get_plugin_defs-1.0.so.0 is in libgstreamermm-1.0-0v5 1.4.3+dfsg-5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgstreamermm_get_plugin_defs-1.0.so.0.0.0