/usr/lib/gcc-cross/mips64el-linux-gnuabi64/7/32/libgcc_s.so.1 is in lib32gcc-7-dev-mips64el-cross 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/mips64el-linux-gnuabi64/7/32/../../../../../mips64el-linux-gnuabi64/libo32/libgcc_s.so.1