[PATCH] add schedule_timeout_{,un}interruptible() interfaces

Add schedule_timeout_{,un}interruptible() interfaces so that
schedule_timeout() callers don't have to worry about forgetting to add the
set_current_state() call beforehand.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>