/usr/x86_64-linux-gnux32/lib64/libcilkrts.so.5 is in lib64cilkrts5-x32-cross 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/x86_64-linux-gnux32/lib64/libcilkrts.so.5.0.0
/usr/x86_64-linux-gnux32/lib64/libcilkrts.so.5.0.0