rcu: Separately compile large rcu_segcblist functions

This commit creates a new kernel/rcu/rcu_segcblist.c file that
contains non-trivial segcblist functions.  Trivial functions
remain as static inline functions in kernel/rcu/rcu_segcblist.h
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

init/Kconfig

@@ -573,6 +573,9 @@ config RCU_STALL_COMMON
 	  the tiny variants to disable RCU CPU stall warnings, while
 	  making these warnings mandatory for the tree variants.
 
+config RCU_NEED_SEGCBLIST
+	def_bool ( TREE_RCU || PREEMPT_RCU || TINY_SRCU || TREE_SRCU )
+
 config CONTEXT_TRACKING
        bool
 

kernel/rcu/Makefile

@@ -12,3 +12,4 @@ obj-$(CONFIG_TREE_RCU) += tree.o
 obj-$(CONFIG_PREEMPT_RCU) += tree.o
 obj-$(CONFIG_TREE_RCU_TRACE) += tree_trace.o
 obj-$(CONFIG_TINY_RCU) += tiny.o
+obj-$(CONFIG_RCU_NEED_SEGCBLIST) += rcu_segcblist.o