[PATCH] alpha sysrq compile fix

missing extern declaration in -Werror land...  Add the proper
declaration to sysrq.h.

include/linux/sysrq.h

@@ -33,6 +33,7 @@ void handle_sysrq(int, struct pt_regs *, struct tty_struct *);
 void __handle_sysrq(int, struct pt_regs *, struct tty_struct *);
 int register_sysrq_key(int, struct sysrq_key_op *);
 int unregister_sysrq_key(int, struct sysrq_key_op *);
+struct sysrq_key_op *__sysrq_get_key_op(int key);
 
 #else