procfs: add conditional compilation check

`proc_timers_operations` is only used when CONFIG_CHECKPOINT_RESTORE is
enabled.

Signed-off-by: Eric Engestrom <eric.engestrom@imgtec.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/base.c

@@ -2158,6 +2158,7 @@ static const struct file_operations proc_map_files_operations = {
 	.llseek		= default_llseek,
 };
 
+#ifdef CONFIG_CHECKPOINT_RESTORE
 struct timers_private {
 	struct pid *pid;
 	struct task_struct *task;
@@ -2256,6 +2257,7 @@ static const struct file_operations proc_timers_operations = {
 	.llseek		= seq_lseek,
 	.release	= seq_release_private,
 };
+#endif
 
 static ssize_t timerslack_ns_write(struct file *file, const char __user *buf,
 					size_t count, loff_t *offset)