rcu-tasks: Fix code-style issues

This commit declares trc_n_readers_need_end and trc_wait static and
replaced a "&" with "&&".  The "&" happened to work because the values
are bool, but accidents waiting to happen and all that...

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/tasks.h

@@ -737,8 +737,8 @@ EXPORT_SYMBOL_GPL(rcu_trace_lock_map);
 
 #ifdef CONFIG_TASKS_TRACE_RCU
 
-atomic_t trc_n_readers_need_end;	// Number of waited-for readers.
-DECLARE_WAIT_QUEUE_HEAD(trc_wait);	// List of holdout tasks.
+static atomic_t trc_n_readers_need_end;		// Number of waited-for readers.
+static DECLARE_WAIT_QUEUE_HEAD(trc_wait);	// List of holdout tasks.
 
 // Record outstanding IPIs to each CPU.  No point in sending two...
 static DEFINE_PER_CPU(bool, trc_ipi_to_cpu);
@@ -845,7 +845,7 @@ static bool trc_inspect_reader(struct task_struct *t, void *arg)
 	bool ofl = cpu_is_offline(cpu);
 
 	if (task_curr(t)) {
-		WARN_ON_ONCE(ofl & !is_idle_task(t));
+		WARN_ON_ONCE(ofl && !is_idle_task(t));
 
 		// If no chance of heavyweight readers, do it the hard way.
 		if (!ofl && !IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB))