/usr/lib/gcc-cross/mipsel-linux-gnu/5/libgcc_s_n32.so is in libn32gcc-5-dev-mipsel-cross 5.5.0-12ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/mipsel-linux-gnu/5/n32/libgcc_s.so