ntfsclone.c: use setmode from header

Fixes linker error:

/usr/lib/gcc/x86_64-pc-cygwin/11/../../../../x86_64-pc-cygwin/bin/ld: ntfsclone.o: in function `open_image':
/cygdrive/e/Documents/Programs/ntfs-3g/ntfsprogs/ntfsclone.c:2385:(.text.startup+0x34e): undefined reference to `setmode'

ntfsprogs/ntfsclone.c

@@ -110,10 +110,14 @@
 #endif
 
 #ifdef HAVE_WINDOWS_H
+#ifdef __CYGWIN__
+#include <io.h>
+#else
 /*
  *		Replacements for functions which do not exist on Windows
  */
 int setmode(int, int); /* from msvcrt.dll */
+#endif
 
 #define getpid() (0)
 #define srandom(seed) srand(seed)