scoutfs: include counters.h for messages

The corruption helpers use counters and callers shouldn't have to
include the counters header themselves.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/msg.h

@@ -3,6 +3,7 @@
 
 #include <linux/bitops.h>
 #include "key.h"
+#include "counters.h"
 
 void __printf(4, 5) scoutfs_msg(struct super_block *sb, const char *prefix,
 				const char *str, const char *fmt, ...);