cpu: add support for gccgo on aix

Change-Id: Icb963d94baf7a1876ce89d0c5fe8cee04bb50629
Reviewed-on: https://go-review.googlesource.com/c/sys/+/233717
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

cpu/cpu_aix.go

@@ -0,0 +1,34 @@
+// Copyright 2019 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.
+
+// +build aix
+
+package cpu
+
+const cacheLineSize = 128
+
+const (
+	// getsystemcfg constants
+	_SC_IMPL     = 2
+	_IMPL_POWER8 = 0x10000
+	_IMPL_POWER9 = 0x20000
+)
+
+func init() {
+	impl := getsystemcfg(_SC_IMPL)
+	if impl&_IMPL_POWER8 != 0 {
+		PPC64.IsPOWER8 = true
+	}
+	if impl&_IMPL_POWER9 != 0 {
+		PPC64.IsPOWER9 = true
+	}
+
+	Initialized = true
+}
+
+func getsystemcfg(label int) (n uint64) {
+	r0, _ := callgetsystemcfg(label)
+	n = uint64(r0)
+	return
+}