Introduce license disclaimer in requested format

analysis/PWGDIL/dielectron/papaframework/PairAnalysisTrackRotator.cxx

+/* Copyright (C) 1998-2009 ALICE Experiment, CERN
+   SPDX-License-Identifier: GPL-3.0-only
+   Authors: Julian Book [committer] */
+
+
 ///////////////////////////////////////////////////////////////////////////
 //                                                                       //
 //                                                                       //

analysis/PWGDIL/dielectron/papaframework/PairAnalysisVarManager.cxx

+/* Copyright (C) 1998-2009 ALICE Experiment, CERN
+   SPDX-License-Identifier: GPL-3.0-only
+   Authors: Julian Book [committer] */
+
 ///////////////////////////////////////////////////////////////////////////
 //                Variables Manager class
 //