/usr/mips64el-linux-gnuabi64/lib/libgfortran.so.3 is in libgfortran3-mips64el-cross 6.4.0-17ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mips64el-linux-gnuabi64/lib/libgfortran.so.3.0.0