TrackTools: update Common CMake copyright header

Replace the obsolete copyright notice in Common/CMakeLists.txt with the current ALICE O2 standard notice.

This resolves the copyright CI finding on PR #15999.

Exact changed-file inventory:
- Common/CMakeLists.txt (copyright notice only)

No CMake logic, C++ source, physics calculations, tests, or tolerances changed.

Validation:
- Exact replacement checksum verified
- One-file Git diff reviewed
- git diff --check passed
- Canonical dEdxAI TrackGeometry: 26 passed, 1 XFAIL
- O2 TrackTools portable tests: 12 passed, 1 XFAIL
- ROOT/ACLiC demonstration: PASS

The previous physics test results refer to the unchanged TrackGeometry header.

Author: miranov25

Common/CMakeLists.txt

@@ -1,12 +1,13 @@
-# Copyright CERN and copyright holders of ALICE O2. This software is distributed
-# under the terms of the GNU General Public License v3 (GPL Version 3), copied
-# verbatim in the file "COPYING".
+# Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+# See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+# All rights not expressly granted are reserved.
 #
-# See http://alice-o2.web.cern.ch/license for full licensing information.
+# This software is distributed under the terms of the GNU General Public
+# License v3 (GPL Version 3), copied verbatim in the file "COPYING".
 #
 # In applying this license CERN does not waive the privileges and immunities
-# granted to it by virtue of its status as an Intergovernmental Organization or
-# submit itself to any jurisdiction.
+# granted to it by virtue of its status as an Intergovernmental Organization
+# or submit itself to any jurisdiction.
 
 add_subdirectory(Constants)
 add_subdirectory(MathUtils)