treewide: Add SPDX license identifier for missed files

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

lib/debug_locks.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * lib/debug_locks.c
  *

lib/fault-inject.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/random.h>

lib/idr.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/bitmap.h>
 #include <linux/bug.h>
 #include <linux/export.h>

lib/interval_tree.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/interval_tree.h>
 #include <linux/interval_tree_generic.h>
 #include <linux/compiler.h>

lib/iov_iter.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/export.h>
 #include <linux/bvec.h>
 #include <linux/uio.h>

lib/math/gcd.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/kernel.h>
 #include <linux/gcd.h>
 #include <linux/export.h>

lib/math/lcm.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/compiler.h>
 #include <linux/gcd.h>
 #include <linux/export.h>

lib/percpu-refcount.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #define pr_fmt(fmt) "%s: " fmt "\n", __func__
 
 #include <linux/kernel.h>

lib/sg_pool.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/module.h>
 #include <linux/scatterlist.h>
 #include <linux/mempool.h>

lib/string_helpers.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Helpers for formatting and printing strings
  *

lib/vsprintf.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  *  linux/lib/vsprintf.c
  *