math: migrate to SPDX identifier

Most tools used for compliance and SBOM generation use SPDX identifiers
This change brings us a step closer to an easy SBOM generation.

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>

math/CMakeLists.txt

@@ -1,6 +1,8 @@
 # ##############################################################################
 # apps/math/CMakeLists.txt
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more contributor
 # license agreements.  See the NOTICE file distributed with this work for
 # additional information regarding copyright ownership.  The ASF licenses this

math/Make.defs

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/Make.defs
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/Makefile

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/gemmlowp/CMakeLists.txt

@@ -1,6 +1,8 @@
 # ##############################################################################
 # apps/math/gemmlowp/CMakeLists.txt
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more contributor
 # license agreements.  See the NOTICE file distributed with this work for
 # additional information regarding copyright ownership.  The ASF licenses this

math/gemmlowp/Make.defs

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/gemmlowp/Make.defs
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/gemmlowp/Makefile

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/gemmlowp/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/kissfft/CMakeLists.txt

@@ -1,6 +1,8 @@
 # ##############################################################################
 # apps/math/kissfft/CMakeLists.txt
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more contributor
 # license agreements.  See the NOTICE file distributed with this work for
 # additional information regarding copyright ownership.  The ASF licenses this

math/kissfft/Make.defs

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/kissfft/Make.defs
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/kissfft/Makefile

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/kissfft/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/libtommath/CMakeLists.txt

@@ -1,6 +1,8 @@
 # ##############################################################################
 # apps/math/libtommath/CMakeLists.txt
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more contributor
 # license agreements.  See the NOTICE file distributed with this work for
 # additional information regarding copyright ownership.  The ASF licenses this

math/libtommath/Make.defs

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/libtommath/Make.defs
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/libtommath/Makefile

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/libtommath/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/ruy/CMakeLists.txt

@@ -1,6 +1,8 @@
 # ##############################################################################
 # apps/math/ruy/CMakeLists.txt
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more contributor
 # license agreements.  See the NOTICE file distributed with this work for
 # additional information regarding copyright ownership.  The ASF licenses this

math/ruy/Make.defs

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/ruy/Make.defs
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The

math/ruy/Makefile

@@ -1,6 +1,8 @@
 ############################################################################
 # apps/math/ruy/Makefile
 #
+# SPDX-License-Identifier: Apache-2.0
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.  The