sysv ipc: remove {msg,sem,shm}sys() declerations

These syscall muxes are under COMPAT7 or earlier and AFACT they were
only ever used in libc.  The which arguments seems to have never had a
published API and it was a mistake that they were exported or declared.

Reviewed by:	kib, jhb
Differential Revision:	https://reviews.freebsd.org/D46209

sys/sys/msg.h

@@ -162,9 +162,6 @@ int msgctl(int, int, struct msqid_ds *);
 int msgget(key_t, int);
 ssize_t msgrcv(int, void *, size_t, long, int);
 int msgsnd(int, const void *, size_t, int);
-#if __BSD_VISIBLE
-int msgsys(int, ...);
-#endif
 __END_DECLS
 #endif /* !_KERNEL */
 

sys/sys/sem.h

@@ -148,9 +148,6 @@ int	kern_get_sema(struct thread *td, struct semid_kernel **res,
 #else /* !_KERNEL */
 
 __BEGIN_DECLS
-#if __BSD_VISIBLE
-int semsys(int, ...);
-#endif
 int semctl(int, int, int, ...);
 int semget(key_t, int, int);
 int semop(int, struct sembuf *, size_t);

sys/sys/shm.h

@@ -171,9 +171,6 @@ typedef __size_t        size_t;
 #endif
 
 __BEGIN_DECLS
-#if __BSD_VISIBLE
-int shmsys(int, ...);
-#endif
 void *shmat(int, const void *, int);
 int shmget(key_t, size_t, int);
 int shmctl(int, int, struct shmid_ds *);