arch: add split IPC system calls where needed

The IPC system call handling is highly inconsistent across architectures,
some use sys_ipc, some use separate calls, and some use both.  We also
have some architectures that require passing IPC_64 in the flags, and
others that set it implicitly.

For the addition of a y2038 safe semtimedop() system call, I chose to only
support the separate entry points, but that requires first supporting
the regular ones with their own syscall numbers.

The IPC_64 is now implied by the new semctl/shmctl/msgctl system
calls even on the architectures that require passing it with the ipc()
multiplexer.

I'm not adding the new semtimedop() or semop() on 32-bit architectures,
those will get implemented using the new semtimedop_time64() version
that gets added along with the other time64 calls.
Three 64-bit architectures (powerpc, s390 and sparc) get semtimedop().

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>

arch/sh/kernel/syscalls/syscall.tbl

@@ -391,3 +391,14 @@
 381	common	preadv2				sys_preadv2
 382	common	pwritev2			sys_pwritev2
 383	common	statx				sys_statx
+# room for arch specific syscalls
+393	common	semget				sys_semget
+394	common	semctl				sys_semctl
+395	common	shmget				sys_shmget
+396	common	shmctl				sys_shmctl
+397	common	shmat				sys_shmat
+398	common	shmdt				sys_shmdt
+399	common	msgget				sys_msgget
+400	common	msgsnd				sys_msgsnd
+401	common	msgrcv				sys_msgrcv
+402	common	msgctl				sys_msgctl