[tlbuild] dvibook failure on Cygwin

[Peter Breitenlohner]

On Sun, 26 Feb 2012, Ken Brown wrote:

> It turned out not to be so hard to sort out.  It was a matter of making sure 
> that getopt gets properly declared (with its prototype).  The attached patch 
> fixes the problem.  With this patch, the declaration is either in the system 
> getopt.h (if unistd.h is included) or in kpathsea/getopt.h.

Hi Ken,

applied (r25513).

The warning

> 'optarg' redeclared without dllimport attribute: previous dllimport ignored

should disappear when <kpathsea/getopt.h> is included before <unistd.h>.
Maybe this should be done in kpathsea/c-unistd.h -- at least for Cygwin.

BTW: can you please comment on the difference, if any, between __CYGWIN__
and __CYGWIN32__!

Regards
Peter