rcu: Convert local functions to static

The rcu_cpu_stall_timeout kernel parameter, the rcu_dynticks per-CPU
variable, and the rcu_gp_fqs() function are used only locally.  This
commit therefore marks them as static.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index e0fa192..2712b89 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -222,7 +222,7 @@
 }
 EXPORT_SYMBOL_GPL(rcu_note_context_switch);
 
-DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
+static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
 	.dynticks_nesting = DYNTICK_TASK_EXIT_IDLE,
 	.dynticks = ATOMIC_INIT(1),
 #ifdef CONFIG_NO_HZ_FULL_SYSIDLE
@@ -1366,7 +1366,7 @@
 /*
  * Do one round of quiescent-state forcing.
  */
-int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
+static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
 {
 	int fqs_state = fqs_state_in;
 	bool isidle = false;