/usr/mips64-linux-gnuabi64/lib/libm.so is in libc6-dev-mips64-cross 2.23-0ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mips64-linux-gnuabi64/lib/libm.so.6
/usr/mips64-linux-gnuabi64/lib/libm.so.6