/usr/mips64el-linux-gnuabi64/lib/libgfortran.so.4 is in libgfortran4-mips64el-cross 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mips64el-linux-gnuabi64/lib/libgfortran.so.4.0.0