This is a long story, but the copyright messages were not added to the files of
AsgTools when this package got included in branch 21.2 back in the day. So we
should just add these one-by-one as we touch these files.

Conflicts:
	Control/AthToolSupport/AsgTools/AsgTools/UnitTest.h
	Control/AthToolSupport/AsgTools/Root/AnaToolHandle.cxx
	Control/AthToolSupport/AsgTools/Root/MessageCheck.cxx
	Control/AthToolSupport/AsgTools/Root/MessagePrinterErrorCollect.cxx
	Control/AthToolSupport/AsgTools/test/gt_AsgTool.cxx
	Control/AthToolSupport/AsgTools/test/gt_MessageCheck.cxx
	Control/AthToolSupport/AsgTools/test/gt_TProperty.cxx
	Control/AthToolSupport/AsgTools/test/gt_UnitTest_test.cxx