um: drivers/xterm.c: fix a file descriptor leak

I could use out_close1, but that seems to be the code path to close the fd
returned by os_create_unix_socket, and using it to close the fd returned
by mkstemp might lead to some confusion, so I don't do it.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/xterm.c

@@ -123,6 +123,7 @@ static int xterm_open(int input, int output, int primary, void *d,
 		err = -errno;
 		printk(UM_KERN_ERR "xterm_open : unlink failed, errno = %d\n",
 		       errno);
+		close(fd);
 		return err;
 	}
 	close(fd);