internal/cpu: add default osinit for ppc64/ppc64le

This will be used for operating systems other than AIX and Linux (both of
which provide a more specific version).

Updates #56001

Change-Id: Ia1de994866b66f03c83696faa92d0531a0b75273
Reviewed-on: https://go-review.googlesource.com/c/go/+/473698
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/internal/cpu/cpu_ppc64x_other.go

@@ -0,0 +1,13 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (ppc64 || ppc64le) && !aix && !linux
+
+package cpu
+
+func osinit() {
+	// Other operating systems do not support reading HWCap from auxiliary vector,
+	// reading privileged system registers or sysctl in user space to detect CPU
+	// features at runtime.
+}