The s390 msgbuf/sembuf/shmbuf header files are all identical to the
version from asm-generic.

This patch removes the files and replaces them with 'generic-y'
statements, to avoid having to modify each copy when we extend sysvipc
to deal with 64-bit time_t in 32-bit user space.

Note that unlike alpha and ia64, the ipcbuf.h header file is slightly
different here, so I'm leaving the private copy.

To deal with 32-bit compat tasks, we also have to adapt the definitions
of compat_{shm,sem,msg}id_ds to match the changes to the respective
asm-generic files.
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>