/usr/lib/x86_64-linux-gnu/libmm-glib.so is in libmm-glib-dev 1.6.8-2ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libmm-glib.so.0.3.0
/usr/lib/x86_64-linux-gnu/libmm-glib.so.0.3.0