uml: handle errors on opening host side of consoles

If the host side of a console can't be opened, this will now produce visible
error messages.

enable_chan now returns a status and this is passed up to con_open and
ssl_open, which will complain if anything went wrong.

The default host device for the serial line driver is now a pts device rather
than a pty device since lots of hosts have LEGACY_PTYS disabled.  This had
always been failing on such hosts, but silently.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/include/chan_kern.h b/arch/um/include/chan_kern.h
index c4b41bb..624b510 100644
--- a/arch/um/include/chan_kern.h
+++ b/arch/um/include/chan_kern.h
@@ -40,7 +40,7 @@
 extern void deactivate_chan(struct list_head *chans, int irq);
 extern void reactivate_chan(struct list_head *chans, int irq);
 extern void chan_enable_winch(struct list_head *chans, struct tty_struct *tty);
-extern void enable_chan(struct line *line);
+extern int enable_chan(struct line *line);
 extern void close_chan(struct list_head *chans, int delay_free_irq);
 extern int chan_window_size(struct list_head *chans, 
 			     unsigned short *rows_out,