Broken build on OpenBSD

[Mark Kettenis]

Hi Simon,

Commit c5819701a3de61e2ba2ef7ad0b616565b32305e5 broke the build on
OpenBSD and probably other non-Linux systems.  ENODATA, which is now
used in fit_check_format(), isn't defined.  It isn't part of POSIX[1]
and generally not available on BSD-derived systems.  Could you pick
another error code for this case?

Thanks,

Mark

[1] It is mentioned in the Open Group Base Specification, however it
    is part of the obsolete XSI STREAMS extension which was never part
    of POSIX proper.