ENH: In superbuild.cmake, CTK-build step can be excluded if SUPERBUILD_EXCLUDE_CTKBUILD_TARGET is set to ON.
ENH: In superbuild.cmake, CTK-build step can be excluded if SUPERBUILD_EXCLUDE_CTKBUILD_TARGET is set to ON.

The variable should be set to ON in case a ctest driver script is
using subproject and want to configure/build/test each one of them
separately. In that specific case, we want to make sure the configure and
build error are not reported when the project is configure/build from the top
level.

jcfr/CTK,danielknorr/CTK,ddao/CTK,msmolens/CTK,ddao/CTK,Heather/CTK,pieper/CTK,finetjul/CTK,fedorov/CTK,lassoan/CTK,laurennlam/CTK,Sardge/CTK,jcfr/CTK,naucoin/CTK,commontk/CTK,laurennlam/CTK,sankhesh/CTK,151706061/CTK,Sardge/CTK,jcfr/CTK,espakm/CTK,espakm/CTK,ddao/CTK,151706061/CTK,vovythevov/CTK,SINTEFMedtek/CTK,danielknorr/CTK,commontk/CTK,pieper/CTK,rkhlebnikov/CTK,SINTEFMedtek/CTK,commontk/CTK,lassoan/CTK,CJGoch/CTK,Sardge/CTK,finetjul/CTK,AndreasFetzer/CTK,Heather/CTK,vovythevov/CTK,Heather/CTK,SINTEFMedtek/CTK,lassoan/CTK,mehrtash/CTK,fedorov/CTK,laurennlam/CTK,CJGoch/CTK,AndreasFetzer/CTK,mehrtash/CTK,Heather/CTK,AndreasFetzer/CTK,naucoin/CTK,laurennlam/CTK,sankhesh/CTK,SINTEFMedtek/CTK,sankhesh/CTK,commontk/CTK,msmolens/CTK,SINTEFMedtek/CTK,vovythevov/CTK,finetjul/CTK,mehrtash/CTK,vovythevov/CTK,151706061/CTK,rkhlebnikov/CTK,sankhesh/CTK,151706061/CTK,danielknorr/CTK,rkhlebnikov/CTK,pieper/CTK,espakm/CTK,AndreasFetzer/CTK,CJGoch/CTK,naucoin/CTK,ddao/CTK,fedorov/CTK,msmolens/CTK,naucoin/CTK,danielknorr/CTK,151706061/CTK,jcfr/CTK,espakm/CTK,lassoan/CTK,CJGoch/CTK,mehrtash/CTK,CJGoch/CTK,fedorov/CTK,rkhlebnikov/CTK,pieper/CTK,Sardge/CTK,msmolens/CTK,finetjul/CTK,jcfr/CTK