/usr/lib/ocaml/native-archs is in ocaml-nox 4.01.0-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1
amd64 armel armhf hurd-i386 i386 kfreebsd-i386 kfreebsd-amd64 lpia powerpc sparc