fdopen link error on Windows

[azverkan]

Git HEAD currently fails to link on x86_64-windows with: unknown symbol fdopen

Switching from fdopen to _fdopen appears to link and pass the tests at least under Windows 10.

https://msdn.microsoft.com/en-us/library/ms235351.aspx
https://msdn.microsoft.com/en-us/library/dye30d82.aspx

[snoyberg]

I think s/fdopen/_fdopen should be fine. Would you be able to test it on your machine? I can push a commit now and confirm that it works for AppVeyor.

Pinging @Blaisorblade.

[Blaisorblade]

I know no objection against _fdopen, and I can confirm the failure on a Win 10 64bit VM with 64 bit stack. AppVeyor tests only with 32bit stack.* Testing on both options would probably be an appropriate response, even though it feels overkill... for no good reason.

*I'm not sure why it worked before, but I suspect it's because of using 32bit stack (on a 64 bit Windows). I think I can rule out a 32bit Windows because I can't find any 32bit IEVM for Win10, but I'm positive I've used 32bit stack.

[snoyberg]

Thanks for confirming, new version uploaded.