FYI: removing HAVE_FCNTL_H tests

[Jim Meyering]

I've just removed all tests for HAVE_FCNTL_H from coreutils.
It's been gone in at least one place since coreutils-5.0 (2004-04-02)
and no one has complained, so I think it's safe to say every system
we care about has fcntl.h, now.

If you know of a system (reasonable portability target)
that lacks fcntl.h, speak now.

Tomorrow I plan to remove all #if HAVE_FCNTL_H tests,
retaining only the `if' branch.  Likewise, there is no
need to check for fcntl.h in .m4 macros.