Fix F_DUPFD_CLOEXEC breakage

Fix a braino in F_DUPFD_CLOEXEC; f_dupfd() expects flags for alloc_fd(),
get_unused_fd() etc and there clone-on-exec if O_CLOEXEC, not
FD_CLOEXEC.

Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fcntl.c

@@ -258,7 +258,7 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 		err = f_dupfd(arg, filp, 0);
 		break;
 	case F_DUPFD_CLOEXEC:
-		err = f_dupfd(arg, filp, FD_CLOEXEC);
+		err = f_dupfd(arg, filp, O_CLOEXEC);
 		break;
 	case F_GETFD:
 		err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;