printk: declare printk_ratelimit_state in ratelimit.h

Adding declaration of printk_ratelimit_state in ratelimit.h removes
potential build breakage and following sparse warning:

kernel/printk.c:1426:1: warning: symbol 'printk_ratelimit_state' was not declared. Should it be static?

[[e-mail]: remove unneeded ifdef]
Signed-off-by: Namhyung Kim <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/ratelimit.h

···
 	rs->begin = 0;
 }
 
+extern struct ratelimit_state printk_ratelimit_state;
+
 extern int ___ratelimit(struct ratelimit_state *rs, const char *func);
 #define __ratelimit(state) ___ratelimit(state, __func__)
 

kernel/sysctl.c

···
 extern int unaligned_dump_stack;
 #endif
 
-extern struct ratelimit_state printk_ratelimit_state;
-
 #ifdef CONFIG_PROC_SYSCTL
 static int proc_do_cad_pid(struct ctl_table *table, int write,
 		  void __user *buffer, size_t *lenp, loff_t *ppos);