The source project of this merge request has been removed.
Ioss_FileInfo.C: use unistd.h instead of sys/unistd.h
Build fails on Musl-based Linux distributions.
As for glibc, sys/unistd.h contains "#include <unistd.h>", thus pointing to unistd.h.
Reference: https://github.com/void-linux/void-packages/pull/40423