ipc: use __ARCH_WANT_IPC_PARSE_VERSION in ipc/util.h

The definition of ipc_parse_version depends on
__ARCH_WANT_IPC_PARSE_VERSION, but the header file declares it
conditionally based on the architecture.

Use the macro consistently to make it easier to add new architectures.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/util.h

@@ -128,7 +128,7 @@ void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
 				      struct ipc64_perm *perm, int extra_perm);
 
-#if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
+#ifndef __ARCH_WANT_IPC_PARSE_VERSION
   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */ 
 # define ipc_parse_version(cmd)	IPC_64
 #else