kmemtrace, rcu: fix linux/rcutree.h and linux/rcuclassic.h dependencies

Impact: build fix for all non-x86 architectures

We want to remove percpu.h from rcuclassic.h/rcutree.h (for upcoming
kmemtrace changes) but that would break the DECLARE_PER_CPU based
declarations in these files.

Move the quiescent counter management functions to their respective
RCU implementation .c files - they were slightly above the inlining
limit anyway.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: paulmck@linux.vnet.ibm.com
LKML-Reference: <1237898630.25315.83.camel@penberg-laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>