/usr/lib/x86_64-linux-gnu/libm17n-flt.so is in libm17n-dev 1.7.0-3+b1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libm17n-flt.so.0.4.1
/usr/lib/x86_64-linux-gnu/libm17n-flt.so.0.4.1