dirchownmod and savewd modules uses unavailable functions under Windows

[Michael Goffioul]

Hi,

While compiling octave under MSVC with current gnulib, I got the following problems (leading undefined references at link stage):

1) dirchownmod uses fchown, but this is not available on Windows and there's no replacement in gnulib

2) savewd uses waitpid, but it doesn't have a dependency on gnulib's waitpid module

3) savewd uses fork, but this is not available on Windows and there's no replacement in gnulib

I'm not sure how to solve 1 and 3, and I suspect MinGW would also be affected (though I didn't test).

Michael.