s390: add missing arch_release_task_struct() declaration

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/thread_info.h

@@ -61,6 +61,8 @@ static inline struct thread_info *current_thread_info(void)
 	return (struct thread_info *) S390_lowcore.thread_info;
 }
 
+void arch_release_task_struct(struct task_struct *tsk);
+
 #define THREAD_SIZE_ORDER THREAD_ORDER
 
 #endif