Merge branch 'mc16dFix' into '21.0-mc16d'

...ple/InDetAlignExample/CalibrationLoopScripts/Solve_trf.py

...etExample/InDetAlignExample/python/IteratorGridClasses.py

...nDetExample/InDetAlignExample/share/AlignmentATNSimple.py

...Example/InDetAlignExample/share/InDetAlignAlgSetup_DBM.py

...tExample/InDetAlignExample/share/NewInDetAlignAlgSetup.py

...ple/InDetAlignExample/share/NewInDetAlignment_DBMRel17.py

...le/InDetAlignExample/share/NewInDetAlignment_Run2Rel17.py

...le/InDetAlignExample/share/NewInDetAlignment_Run2Rel19.py

Tracking/TrkAlignment/TrkAlgebraUtils/CMakeLists.txt

...king/TrkAlignment/TrkAlgebraUtils/TrkAlgebraUtils/AlMat.h

...g/TrkAlignment/TrkAlgebraUtils/TrkAlgebraUtils/AlSpaMat.h

...g/TrkAlignment/TrkAlgebraUtils/TrkAlgebraUtils/AlSymMat.h

...kAlignment/TrkAlgebraUtils/TrkAlgebraUtils/AlSymMatBase.h

...king/TrkAlignment/TrkAlgebraUtils/TrkAlgebraUtils/AlVec.h

...ing/TrkAlignment/TrkAlgebraUtils/TrkAlgebraUtils/IntVec.h

Tracking/TrkAlignment/TrkAlgebraUtils/cmt/requirements

Tracking/TrkAlignment/TrkAlgebraUtils/src/AlMat.cxx

Tracking/TrkAlignment/TrkAlgebraUtils/src/AlSpaMat.cxx

Tracking/TrkAlignment/TrkAlgebraUtils/src/AlSymMat.cxx

Tracking/TrkAlignment/TrkAlgebraUtils/src/AlSymMatBase.cxx