In ResetClassInfo, do not use SetClassInfo.
In ResetClassInfo, do not use SetClassInfo.

Just delete the ClassInfo and rely on the TClass' state to be accurate/good enough to
recreate the ClassInfo when needed.

This (and the related commits) fixes ROOT-6804 and ROOT-6806

buuck/root,Y--/root,gganis/root,satyarth934/root,sbinet/cxx-root,CristinaCristescu/root,veprbl/root,nilqed/root,abhinavmoudgil95/root,esakellari/my_root_for_test,dfunke/root,omazapa/root,bbockelm/root,jrtomps/root,esakellari/my_root_for_test,buuck/root,satyarth934/root,simonpf/root,BerserkerTroll/root,agarciamontoro/root,pspe/root,gbitzes/root,mhuwiler/rootauto,agarciamontoro/root,agarciamontoro/root,vukasinmilosevic/root,karies/root,thomaskeck/root,gbitzes/root,satyarth934/root,satyarth934/root,arch1tect0r/root,BerserkerTroll/root,dfunke/root,omazapa/root-old,perovic/root,krafczyk/root,thomaskeck/root,abhinavmoudgil95/root,zzxuanyuan/root-compressor-dummy,sirinath/root,omazapa/root,evgeny-boger/root,perovic/root,karies/root,simonpf/root,Y--/root,veprbl/root,esakellari/root,karies/root,lgiommi/root,gbitzes/root,Y--/root,perovic/root,davidlt/root,olifre/root,jrtomps/root,perovic/root,zzxuanyuan/root-compressor-dummy,lgiommi/root,BerserkerTroll/root,perovic/root,root-mirror/root,zzxuanyuan/root-compressor-dummy,bbockelm/root,simonpf/root,evgeny-boger/root,davidlt/root,veprbl/root,evgeny-boger/root,sawenzel/root,root-mirror/root,buuck/root,mattkretz/root,omazapa/root-old,zzxuanyuan/root,krafczyk/root,buuck/root,Duraznos/root,root-mirror/root,beniz/root,abhinavmoudgil95/root,sawenzel/root,zzxuanyuan/root-compressor-dummy,perovic/root,lgiommi/root,beniz/root,bbockelm/root,lgiommi/root,mkret2/root,nilqed/root,nilqed/root,georgtroska/root,gbitzes/root,esakellari/root,davidlt/root,thomaskeck/root,omazapa/root-old,arch1tect0r/root,krafczyk/root,olifre/root,sirinath/root,zzxuanyuan/root-compressor-dummy,Duraznos/root,mhuwiler/rootauto,Y--/root,mhuwiler/rootauto,omazapa/root-old,thomaskeck/root,nilqed/root,veprbl/root,root-mirror/root,davidlt/root,Duraznos/root,abhinavmoudgil95/root,Duraznos/root,esakellari/my_root_for_test,simonpf/root,arch1tect0r/root,zzxuanyuan/root,pspe/root,Y--/root,olifre/root,esakellari/my_root_for_test,gganis/root,vukasinmilosevic/root,olifre/root,buuck/root,omazapa/root-old,georgtroska/root,buuck/root,arch1tect0r/root,sirinath/root,mkret2/root,CristinaCristescu/root,jrtomps/root,gganis/root,root-mirror/root,BerserkerTroll/root,beniz/root,zzxuanyuan/root,davidlt/root,nilqed/root,krafczyk/root,simonpf/root,dfunke/root,esakellari/root,nilqed/root,arch1tect0r/root,gbitzes/root,thomaskeck/root,CristinaCristescu/root,vukasinmilosevic/root,veprbl/root,olifre/root,sawenzel/root,karies/root,veprbl/root,gganis/root,pspe/root,sbinet/cxx-root,BerserkerTroll/root,vukasinmilosevic/root,jrtomps/root,beniz/root,buuck/root,evgeny-boger/root,mkret2/root,zzxuanyuan/root-compressor-dummy,sirinath/root,mkret2/root,mhuwiler/rootauto,georgtroska/root,sbinet/cxx-root,dfunke/root,CristinaCristescu/root,omazapa/root,simonpf/root,mattkretz/root,mattkretz/root,esakellari/my_root_for_test,gbitzes/root,mattkretz/root,krafczyk/root,beniz/root,zzxuanyuan/root-compressor-dummy,bbockelm/root,sirinath/root,pspe/root,zzxuanyuan/root,vukasinmilosevic/root,karies/root,esakellari/root,mkret2/root,jrtomps/root,CristinaCristescu/root,karies/root,root-mirror/root,krafczyk/root,sawenzel/root,zzxuanyuan/root-compressor-dummy,dfunke/root,sirinath/root,agarciamontoro/root,bbockelm/root,nilqed/root,abhinavmoudgil95/root,beniz/root,omazapa/root,mhuwiler/rootauto,abhinavmoudgil95/root,mkret2/root,georgtroska/root,Y--/root,omazapa/root,mattkretz/root,gbitzes/root,mkret2/root,gbitzes/root,dfunke/root,beniz/root,perovic/root,mhuwiler/rootauto,thomaskeck/root,CristinaCristescu/root,esakellari/root,arch1tect0r/root,dfunke/root,arch1tect0r/root,pspe/root,karies/root,thomaskeck/root,pspe/root,mhuwiler/rootauto,davidlt/root,mattkretz/root,Duraznos/root,jrtomps/root,omazapa/root,omazapa/root-old,omazapa/root-old,abhinavmoudgil95/root,Duraznos/root,buuck/root,olifre/root,sbinet/cxx-root,evgeny-boger/root,veprbl/root,esakellari/my_root_for_test,gganis/root,pspe/root,gganis/root,davidlt/root,perovic/root,sbinet/cxx-root,olifre/root,omazapa/root,vukasinmilosevic/root,pspe/root,perovic/root,evgeny-boger/root,zzxuanyuan/root,omazapa/root-old,abhinavmoudgil95/root,dfunke/root,Duraznos/root,satyarth934/root,vukasinmilosevic/root,agarciamontoro/root,esakellari/root,zzxuanyuan/root,georgtroska/root,karies/root,veprbl/root,sbinet/cxx-root,nilqed/root,krafczyk/root,bbockelm/root,thomaskeck/root,BerserkerTroll/root,agarciamontoro/root,agarciamontoro/root,mhuwiler/rootauto,bbockelm/root,lgiommi/root,omazapa/root-old,vukasinmilosevic/root,esakellari/root,nilqed/root,esakellari/root,georgtroska/root,karies/root,BerserkerTroll/root,mkret2/root,arch1tect0r/root,simonpf/root,sirinath/root,gganis/root,olifre/root,lgiommi/root,esakellari/my_root_for_test,bbockelm/root,sirinath/root,CristinaCristescu/root,sbinet/cxx-root,omazapa/root-old,root-mirror/root,BerserkerTroll/root,gganis/root,zzxuanyuan/root,Duraznos/root,perovic/root,dfunke/root,bbockelm/root,evgeny-boger/root,olifre/root,buuck/root,CristinaCristescu/root,agarciamontoro/root,evgeny-boger/root,satyarth934/root,nilqed/root,vukasinmilosevic/root,gganis/root,omazapa/root,mattkretz/root,jrtomps/root,sbinet/cxx-root,veprbl/root,beniz/root,sbinet/cxx-root,zzxuanyuan/root-compressor-dummy,karies/root,sirinath/root,BerserkerTroll/root,perovic/root,mhuwiler/rootauto,davidlt/root,esakellari/root,veprbl/root,bbockelm/root,davidlt/root,jrtomps/root,sawenzel/root,georgtroska/root,jrtomps/root,mhuwiler/rootauto,Duraznos/root,satyarth934/root,mattkretz/root,krafczyk/root,mattkretz/root,sawenzel/root,beniz/root,Y--/root,omazapa/root,mkret2/root,Y--/root,gganis/root,gbitzes/root,mattkretz/root,buuck/root,pspe/root,gganis/root,arch1tect0r/root,karies/root,lgiommi/root,simonpf/root,root-mirror/root,dfunke/root,lgiommi/root,Duraznos/root,simonpf/root,georgtroska/root,bbockelm/root,mattkretz/root,esakellari/my_root_for_test,thomaskeck/root,sawenzel/root,zzxuanyuan/root-compressor-dummy,CristinaCristescu/root,sbinet/cxx-root,evgeny-boger/root,gbitzes/root,evgeny-boger/root,esakellari/root,root-mirror/root,root-mirror/root,arch1tect0r/root,omazapa/root,vukasinmilosevic/root,evgeny-boger/root,vukasinmilosevic/root,georgtroska/root,dfunke/root,Y--/root,mkret2/root,sawenzel/root,agarciamontoro/root,zzxuanyuan/root,pspe/root,georgtroska/root,agarciamontoro/root,root-mirror/root,lgiommi/root,Y--/root,buuck/root,gbitzes/root,abhinavmoudgil95/root,agarciamontoro/root,satyarth934/root,zzxuanyuan/root,krafczyk/root,satyarth934/root,krafczyk/root,BerserkerTroll/root,Duraznos/root,lgiommi/root,CristinaCristescu/root,sirinath/root,satyarth934/root,omazapa/root-old,sawenzel/root,beniz/root,jrtomps/root,olifre/root,krafczyk/root,Y--/root,arch1tect0r/root,sawenzel/root,olifre/root,omazapa/root,simonpf/root,mhuwiler/rootauto,esakellari/my_root_for_test,georgtroska/root,davidlt/root,jrtomps/root,BerserkerTroll/root,beniz/root,zzxuanyuan/root,CristinaCristescu/root,simonpf/root,thomaskeck/root,satyarth934/root,mkret2/root,davidlt/root,veprbl/root,pspe/root,zzxuanyuan/root,zzxuanyuan/root,esakellari/my_root_for_test,lgiommi/root,zzxuanyuan/root-compressor-dummy,abhinavmoudgil95/root,sawenzel/root,sirinath/root,nilqed/root,abhinavmoudgil95/root,esakellari/root,sbinet/cxx-root