* winlean.h: Make sure certain Windows macros are undefined again.

Add comment to explain why.
	* winsup.h: Include winlean.h from C sources as well.
	* libc/minires-os-if.c: Drop including ntdef.h.

	Fix previous ChangeLog entry.

winsup/cygwin/libc/minires-os-if.c

@@ -16,7 +16,6 @@ details. */
 #include <ws2tcpip.h>
 #include <iphlpapi.h>
 #include <windns.h>
-#include <ntdef.h>
 #include "ntdll.h"
 #undef h_errno
 #include "minires.h"