[dev.ssa] cmd/compile/internal/ssa: add missing copyright notices

Change-Id: I9d4e0f3e9afc9920ee0d77b0073ac8597c7c048f
Reviewed-on: https://go-review.googlesource.com/10756Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/func_test.go

+// Copyright 2015 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.
+
 // This file contains some utility functions to help define Funcs for testing.
 // As an example, the following func
 //

src/cmd/compile/internal/ssa/regalloc.go

+// Copyright 2015 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 ssa
 
 import (

src/cmd/compile/internal/ssa/stackalloc.go

+// Copyright 2015 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 ssa
 
 import "log"