K 10
svn:author
V 3
avg
K 8
svn:date
V 27
2012-10-06T20:01:17.606781Z
K 7
svn:log
V 507
boot/console: handle consoles that fail to probe

- clarify meaning of console flags
- perform i/o via a console only if both of the following conditions are met:
   o console is active (selected by user or config)
   o console flags that it can perform the operation
- warn if a chosen console can not work (the warning may go nowhere without
  working and active console, though)

Reviewed by:	jhb
Tested by:	Uffe Jakobsen <uffe@uffe.org>,
		Olivier Cochard-Labbe' <olivier@cochard.me>
MFC after:	26 days

END