Pull RCU updates from Paul E. McKenney:
1.	Changes to rcutorture and to RCU documentation. Posted to LKML at
        https://lkml.org/lkml/2013/1/26/188.
2.	Enhancements to uniprocessor handling in tiny RCU. Posted to LKML
        at https://lkml.org/lkml/2013/1/27/2.
3.	Tag RCU callbacks with grace-period number to simplify callback
        advancement. Posted to LKML at https://lkml.org/lkml/2013/1/26/203.
4.	Miscellaneous fixes. Posted to LKML at https://lkml.org/lkml/2013/1/26/204.
Signed-off-by: Ingo Molnar <mingo@kernel.org>