* fhandler_serial.cc: Fix includes for IOCTL codes to support Mingw64.

* fhandler_tape.cc: Ditto.
	* flock.cc (allow_others_to_sync): Use PISECURITY_DESCRIPTOR since
	PSECURITY_DESCRIPTOR is supposed to be the opaque type.
	* ntdll.h: Remove CreateDisposition flags again, now that they are
	defined in Mingw64's ntdef.h.  Ditto for Create/Open flags.

winsup/cygwin/fhandler_tape.cc

@@ -15,7 +15,12 @@ details. */
 #include <stdlib.h>
 #include <sys/mtio.h>
 #include <sys/param.h>
+#ifdef __MINGW64_VERSION_MAJOR
+#include <devioctl.h>
+#include <ntddstor.h>
+#else
 #include <ddk/ntddstor.h>
+#endif
 #include "security.h"
 #include "path.h"
 #include "fhandler.h"