[PATCH] Add deprecated_for_modules

Add a deprecated_for_modules macro that allows symbols to be deprecated only
when used by modules, as suggested by Andrew Morton some months back.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>