/usr/sh4-linux-gnu/lib/libgfortran.so.3 is in libgfortran3-sh4-cross 6.3.0-18cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/sh4-linux-gnu/lib/libgfortran.so.3.0.0
/usr/sh4-linux-gnu/lib/libgfortran.so.3.0.0