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

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build aix,ppc64
+// +build aix
 
 package cpu
 

cpu/syscall_aix_gccgo.go

@@ -0,0 +1,27 @@
+// Copyright 2020 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.
+
+// Recreate a getsystemcfg syscall handler instead of
+// using the one provided by x/sys/unix to avoid having
+// the dependency between them. (See golang.org/issue/32102)
+// Morever, this file will be used during the building of
+// gccgo's libgo and thus must not used a CGo method.
+
+// +build aix
+// +build gccgo
+
+package cpu
+
+import (
+	"syscall"
+)
+
+//extern getsystemcfg
+func gccgoGetsystemcfg(label uint32) (r uint64)
+
+func callgetsystemcfg(label int) (r1 uintptr, e1 syscall.Errno) {
+	r1 = uintptr(gccgoGetsystemcfg(uint32(label)))
+	e1 = syscall.GetErrno()
+	return
+}