/usr/mipsel-linux-gnu/lib64/libgfortran.so.4 is in lib64gfortran4-mipsel-cross 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mipsel-linux-gnu/lib64/libgfortran.so.4.0.0
/usr/mipsel-linux-gnu/lib64/libgfortran.so.4.0.0