misc: Replace license blurb with kernel-style SPDX markers

This was roughly achieved by the following shell script:

$ git ls-files |
	grep '\.[ch]p*$' |
	while read F; do EXT=${F##*.}; cat spdx.$EXT <(sed '/^\/\*$/,/^ \*\/$/d' $F) > ${F}.tmp; mv ${F}.tmp $F; done

With the following context:

$ cat spdx.c
// SPDX-License-Identifier: Apache-2.0
// Copyright (C) 2018 IBM Corp.
$ cat spdx.h
/* SPDX-License-Identifier: Apache-2.0 */
/* Copyright (C) 2018 IBM Corp. */
$ ls -l spdx.*
-rw-r--r-- 1 andrew andrew 71 Feb 27 12:02 spdx.c
lrwxrwxrwx 1 andrew andrew  6 Feb 27 12:02 spdx.cpp -> spdx.c
-rw-r--r-- 1 andrew andrew 77 Feb 27 12:02 spdx.h
lrwxrwxrwx 1 andrew andrew  6 Feb 27 12:02 spdx.hpp -> spdx.h

The `sed` invocation catches a lot of function documentation, so the
hunks were manually added to avoid removing information that we want to
keep.

Change-Id: I63e49ca2593aa0db0568c7a63bfdead388642e76
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/common.c b/common.c
index 540cec5..c0497fd 100644
--- a/common.c
+++ b/common.c
@@ -1,19 +1,5 @@
-/* Copyright 2016 IBM
- *
- * 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.
- *
- */
-
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (C) 2018 IBM Corp.
 #define _GNU_SOURCE
 #include <stdarg.h>
 #include <stdbool.h>