all: add empty line between copyright header and package clause

Makes sure the copyright notice is not interpreted as the package level
godoc.

Change-Id: I2afce7c9d620f19d51ec1438b1d0db1774b57146
Reviewed-on: https://go-review.googlesource.com/c/go/+/248760
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

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

@@ -1,6 +1,7 @@
 // Copyright 2017 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/passbm_test.go

@@ -1,6 +1,7 @@
 // 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/go/internal/trace/trace.go

@@ -1,6 +1,7 @@
 // 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.
+
 package trace
 
 import (

src/cmd/link/internal/benchmark/bench_test.go

@@ -1,6 +1,7 @@
 // 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.
+
 package benchmark
 
 import (

src/cmd/link/internal/ld/errors.go

@@ -1,6 +1,7 @@
 // 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.
+
 package ld
 
 import (

src/runtime/closure_test.go

@@ -1,6 +1,7 @@
 // Copyright 2011 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 runtime_test
 
 import "testing"

src/runtime/map_benchmark_test.go

@@ -1,6 +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 runtime_test
 
 import (

src/runtime/slice_test.go

@@ -1,6 +1,7 @@
 // Copyright 2011 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 runtime_test
 
 import (

src/sync/cond_test.go

@@ -1,6 +1,7 @@
 // Copyright 2011 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 sync_test
 
 import (

test/fixedbugs/issue15281.go

@@ -3,6 +3,7 @@
 // Copyright 2016 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 main
 
 import "runtime"