exp/ssa/interp: fix MS Windows breakage.

syscall.{Kill,Write} are not portable to MS Windows, so we
disable them for now.

R=iant, rsc
CC=golang-dev
https://golang.org/cl/7312066

src/pkg/exp/ssa/interp/external.go

@@ -1,3 +1,7 @@
+// Copyright 2013 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 interp
 
 // Emulated functions that we cannot interpret because they are
@@ -173,26 +177,6 @@ func ext۰syscall۰Getpid(fn *ssa.Function, args []value, slots []value) value {
 	return syscall.Getpid()
 }
 
-func ext۰syscall۰Kill(fn *ssa.Function, args []value, slots []value) value {
-	// We could emulate syscall.Syscall but it's more effort.
-	err := syscall.Kill(args[0].(int), syscall.Signal(args[1].(int)))
-	err = err // TODO(adonovan): fix: adapt concrete err to interpreted iface (e.g. call interpreted errors.New)
-	return iface{}
-}
-
-func ext۰syscall۰Write(fn *ssa.Function, args []value, slots []value) value {
-	// We could emulate syscall.Syscall but it's more effort.
-	p := args[1].([]value)
-	b := make([]byte, 0, len(p))
-	for i := range p {
-		b = append(b, p[i].(byte))
-	}
-	n, _ := syscall.Write(args[0].(int), b)
-	err := iface{} // TODO(adonovan): fix: adapt concrete err to interpreted iface.
-	return tuple{n, err}
-
-}
-
 // The set of remaining native functions we need to implement (as needed):
 
 // bytes/bytes.go:42:func Equal(a, b []byte) bool

src/pkg/exp/ssa/interp/external_unix.go

@@ -0,0 +1,32 @@
+// Copyright 2013 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 !windows,!plan9
+
+package interp
+
+import (
+	"exp/ssa"
+	"syscall"
+)
+
+func ext۰syscall۰Kill(fn *ssa.Function, args []value, slots []value) value {
+	// We could emulate syscall.Syscall but it's more effort.
+	err := syscall.Kill(args[0].(int), syscall.Signal(args[1].(int)))
+	err = err // TODO(adonovan): fix: adapt concrete err to interpreted iface (e.g. call interpreted errors.New)
+	return iface{}
+}
+
+func ext۰syscall۰Write(fn *ssa.Function, args []value, slots []value) value {
+	// We could emulate syscall.Syscall but it's more effort.
+	p := args[1].([]value)
+	b := make([]byte, 0, len(p))
+	for i := range p {
+		b = append(b, p[i].(byte))
+	}
+	n, _ := syscall.Write(args[0].(int), b)
+	err := iface{} // TODO(adonovan): fix: adapt concrete err to interpreted iface.
+	return tuple{n, err}
+
+}

src/pkg/exp/ssa/interp/external_windows.go

@@ -0,0 +1,19 @@
+// Copyright 2013 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 windows plan9
+
+package interp
+
+import (
+	"exp/ssa"
+)
+
+func ext۰syscall۰Kill(fn *ssa.Function, args []value, slots []value) value {
+	panic("syscall.Kill not yet implemented")
+}
+
+func ext۰syscall۰Write(fn *ssa.Function, args []value, slots []value) value {
+	panic("syscall.Write not yet implemented")
+}