syscall: add const ARCH, analogous to OS

R=r
CC=giles, golang-dev
https://golang.org/cl/600041

src/pkg/syscall/Makefile

@@ -9,6 +9,7 @@ GOFILES=\
 	errstr.go\
 	exec.go\
 	syscall.go\
+	syscall_$(GOARCH).go\
 	syscall_$(GOOS).go\
 	syscall_$(GOOS)_$(GOARCH).go\
 	zerrors_$(GOOS)_$(GOARCH).go\

src/pkg/syscall/syscall_386.go

+// Copyright 2010 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.
+
+package syscall
+
+const ARCH = "386"

src/pkg/syscall/syscall_amd64.go

+// Copyright 2010 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.
+
+package syscall
+
+const ARCH = "amd64"

src/pkg/syscall/syscall_arm.go

+// Copyright 2010 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.
+
+package syscall
+
+const ARCH = "arm"