treewide: add license header and enable haslicense linter

Change-Id: I873a8d4082d75e8f813d8a726a41187eea7a065e
Reviewed-on: https://review.monogon.dev/c/monogon/+/3825
Tested-by: Jenkins CI
Reviewed-by: Leopold Schabel <leo@monogon.tech>
diff --git a/osbase/devicemapper/ctype.go b/osbase/devicemapper/ctype.go
index 05e6934..28e7b5c 100644
--- a/osbase/devicemapper/ctype.go
+++ b/osbase/devicemapper/ctype.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package devicemapper
 
 // Linux kernel ctype data from @linux//include/linux:ctype.h
diff --git a/osbase/devicemapper/devicemapper.go b/osbase/devicemapper/devicemapper.go
index 1999a00..3c7acc1 100644
--- a/osbase/devicemapper/devicemapper.go
+++ b/osbase/devicemapper/devicemapper.go
@@ -1,18 +1,5 @@
-// Copyright 2020 The Monogon Project Authors.
-//
+// Copyright The Monogon Project Authors.
 // SPDX-License-Identifier: Apache-2.0
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
 
 // package devicemapper is a thin wrapper for the devicemapper ioctl API.
 // See: https://github.com/torvalds/linux/blob/master/include/uapi/linux/dm-ioctl.h