ipc: Remove unused declaration of recompute_msgmni

The function recompute_msgmni was removed a while ago
but it is still declared in a header file remove it.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

ipc/util.h

@@ -153,8 +153,6 @@ extern struct msg_msg *load_msg(const void __user *src, size_t len);
 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 
-extern void recompute_msgmni(struct ipc_namespace *);
-
 static inline int ipc_buildid(int id, int seq)
 {
 	return SEQ_MULTIPLIER * seq + id;