IPC server: NetBSD sync, general improvements

- switch to the NetBSD identifier system; it is not only better, but
  also required for porting NetBSD ipcs(1) and ipcrm(1); however, it
  requires that slots not be moved, and that results in some changes;
- synchronize some other things with NetBSD: where keys are kept, as
  well as various non-permission mode flags;
- fix semctl(2) vararg retrieval and message field type;
- use SUSPEND instead of weird reply exceptions in the call table;
- fix several memory leaks and at least one missing permission check;
- improve the atomicity of semop(2) by a small amount, even though
  its atomicity is still broken at a fundamental level;
- use the new cheaper way to retrieve the current time;
- resolve all level-5 LLVM warnings.

Change-Id: I0c47aacde478b23bb77d628384aeab855a22fdbf

sys/sys/sem.h

@@ -187,11 +187,13 @@ struct sem_sysctl_info {
 /* actual size of an undo structure */
 #define SEMUSZ	(sizeof(struct sem_undo)+sizeof(struct sem_undo_entry)*SEMUME)
 
+#ifndef __minix
 /*
  * Structures allocated in machdep.c
  */
 extern struct seminfo seminfo;
 extern struct semid_ds *sema;		/* semaphore id pool */
+#endif /* !__minix */
 
 /*
  * Parameters to the semconfig system call

sys/sys/shm.h

@@ -215,12 +215,12 @@ struct shm_info
        unsigned long int swap_successes;
 };
 
-#define SHMMNI 4096
+#define SHMMNI 1024
 #define SHMSEG 32              /* max shared segs per process */
 
-/* shm_mode upper byte flags */
-#define SHM_DEST 01000                 /* segment will be destroyed on last detach */
-#define SHM_LOCKED 02000               /* segment will not be swapped */
+/* Public shm_perm.mode flags, synchronized with NetBSD kernel values above */
+#define SHM_DEST	0x0400	/* destroy on last detach (SHMSEG_REMOVED) */
+#define SHM_LOCKED	0x4000	/* pages will not be swapped (SHMSEG_WIRED) */
 
 #endif /* defined(__minix) */