Correct license for build system files

According to QUIP-18 [1], all build system
files should be BSD-3-Clause

[1]: https://contribute.qt-project.org/quips/18

Pick-to: 6.7
Task-number: QTBUG-121787
Change-Id: I70ac22ec6c8ec1e0917e2c24c91ec2046d3ca822
Reviewed-by: Kai Köhne <kai.koehne@qt.io>

config.tests/bluez/main.cpp

@@ -1,5 +1,5 @@
 // Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+// SPDX-License-Identifier: BSD-3-Clause
 
 #include <bluetooth/bluetooth.h>
 

config.tests/bluez_le/main.cpp

@@ -1,5 +1,5 @@
 // Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+// SPDX-License-Identifier: BSD-3-Clause
 
 #include <bluetooth/bluetooth.h>
 #include <bluetooth/l2cap.h>

config.tests/linux_crypto_api/main.cpp

@@ -1,5 +1,5 @@
 // Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+// SPDX-License-Identifier: BSD-3-Clause
 
 #include <linux/if_alg.h>
 #include <sys/socket.h>

config.tests/winrt_bt/main.cpp

@@ -1,5 +1,5 @@
 // Copyright (C) 2017 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+// SPDX-License-Identifier: BSD-3-Clause
 
 #include <wrl.h>
 #include <windows.devices.enumeration.h>