inet_* functions on Windows

Unfortunately, these headers are "interesting" on Windows. They
absolutely have to be included prior to <windows.h> which is included
from other system headers (nu surprise there). In some earlier version
of this patch this was not a problem, but I suspect that our
config.h-ification for the `LIBYANG_API_{DEF,DECL}` made stuff more
complex :(.

TL;DR: make sure that our "compat.h" goes in first, otherwise Bad
Things™ happen.
diff --git a/compat/posix-shims/unistd.h b/compat/posix-shims/unistd.h
index 85040b2..95bcecc 100644
--- a/compat/posix-shims/unistd.h
+++ b/compat/posix-shims/unistd.h
@@ -1,6 +1,10 @@
 #ifndef _UNISTD_H
 #define _UNISTD_H    1
 
+/* headers are broken on Windows, which means that some of them simply *have* to come first */
+# include <winsock2.h>
+# include <ws2tcpip.h>
+
 /* This is intended as a drop-in replacement for unistd.h on Windows.
  * Please add functionality as neeeded.
  * https://stackoverflow.com/a/826027/1202830