Add brief license headers to tests

These are effectively public-domain, but use apache2.0 to avoid adding new licenses

tests/gtests/blenlib/BLI_math_color_test.cc

@@ -1,3 +1,5 @@
+/* Apache License, Version 2.0 */
+
 #include "testing/testing.h"
 
 #include "BLI_math.h"

tests/gtests/blenlib/BLI_math_geom_test.cc

@@ -1,3 +1,5 @@
+/* Apache License, Version 2.0 */
+
 #include "testing/testing.h"
 
 #include "BLI_math.h"

tests/gtests/blenlib/BLI_path_util_test.cc

@@ -1,3 +1,5 @@
+/* Apache License, Version 2.0 */
+
 #include "testing/testing.h"
 
 extern "C" {

tests/gtests/guardedalloc/guardedalloc_alignment_test.cc

@@ -1,3 +1,5 @@
+/* Apache License, Version 2.0 */
+
 #include "testing/testing.h"
 
 #include "MEM_guardedalloc.h"

tests/python/bl_pyapi_mathutils.py

@@ -1,3 +1,5 @@
+# Apache License, Version 2.0
+
 # ./blender.bin --background -noaudio --python tests/python/bl_pyapi_mathutils.py
 import unittest
 from test import support

tests/python/bl_pyapi_units.py

@@ -1,3 +1,5 @@
+# Apache License, Version 2.0
+
 # ./blender.bin --background -noaudio --python tests/python/bl_pyapi_units.py
 import unittest
 from test import support

tests/python/rna_array.py

@@ -1,20 +1,4 @@
-# ##### BEGIN GPL LICENSE BLOCK #####
-#
-#  This program is free software; you can redistribute it and/or
-#  modify it under the terms of the GNU General Public License
-#  as published by the Free Software Foundation; either version 2
-#  of the License, or (at your option) any later version.
-# 
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#  GNU General Public License for more details.
-# 
-#  You should have received a copy of the GNU General Public License
-#  along with this program; if not, write to the Free Software Foundation,
-#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
-#
-# ##### END GPL LICENSE BLOCK #####
+# Apache License, Version 2.0
 
 import unittest
 import random