Fix include/bits/ipc.h for header conformance tests

[Roland McGrath]

None of that stuff belongs there at all.  The IPCOP_* macros are already in
sysdeps/unix/sysv/linux/ipc_priv.h and that's where they belong.
__syscall_ipc does not seem to actually exist, so its declaration is dead.

So I think the right fix should be just to remove include/bits/ipc.h
altogether.  Off hand I suspect that will just work as is.  If it breaks
anything, it should be nothing more than a missing #include <ipc_priv.h>.
i?86 should be a sufficient build to test that change.

sysdeps/unix/sysv/linux/powerpc/bits/ipc.h (the installed header) also
declares __ipc (which does not exist) and defines the IPCOP_* macros.
Those should not be there either.  Those probably won't cause any
conformtest failures on powerpc since the macros are in #ifdef __USE_GNU
and the declaration is an __ name.  But they should go.


Thanks,
Roland