[PATCH] sched/fair: fix build warning about undefined test_idle_cores()

[qiwuchen55@gmail.com]

From: chenqiwu <chenqiwu@xiaomi.com>

The build with arm64's defconfig:
CONFIG_SCHED_MC=y
# CONFIG_SCHED_SMT is not set

Trigger the following warning due to test_idle_cores()'s definition
missing:
kernel/sched/fair.c:1524:20: warning: ‘test_idle_cores’ declared ‘static’
	but never defined [-Wunused-function]

Move the CONFIG_SCHED_SMT ifdeffery around test_idle_cores()'s declaration
to fix it.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
---
 kernel/sched/fair.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 84594f8..d11d965 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1520,8 +1520,10 @@ static inline bool is_core_idle(int cpu)
 	return true;
 }
 
+#ifdef CONFIG_SCHED_SMT
 /* Forward declarations of select_idle_sibling helpers */
 static inline bool test_idle_cores(int cpu, bool def);
+#endif
 
 struct task_numa_env {
 	struct task_struct *p;
-- 
1.9.1