Make variable used for GUID of TKeys atomic
Make variable used for GUID of TKeys atomic

Since TKeys can be made by different threads, it is necessary to
protect the global used to assign the GUID of TKeys,  keyAbsNumber
so that we are guaranteed to get a unique value for each request.
C++11 atomics give that guarantee.

abhinavmoudgil95/root,georgtroska/root,lgiommi/root,nilqed/root,gganis/root,satyarth934/root,davidlt/root,olifre/root,mhuwiler/rootauto,mhuwiler/rootauto,sawenzel/root,Duraznos/root,buuck/root,sirinath/root,mhuwiler/rootauto,georgtroska/root,dfunke/root,Duraznos/root,agarciamontoro/root,pspe/root,BerserkerTroll/root,pspe/root,evgeny-boger/root,karies/root,esakellari/my_root_for_test,mattkretz/root,jrtomps/root,satyarth934/root,gganis/root,satyarth934/root,gbitzes/root,buuck/root,esakellari/root,CristinaCristescu/root,krafczyk/root,thomaskeck/root,dfunke/root,Duraznos/root,jrtomps/root,krafczyk/root,abhinavmoudgil95/root,vukasinmilosevic/root,vukasinmilosevic/root,jrtomps/root,omazapa/root,mkret2/root,Y--/root,sirinath/root,zzxuanyuan/root,evgeny-boger/root,gganis/root,sawenzel/root,davidlt/root,esakellari/my_root_for_test,evgeny-boger/root,nilqed/root,Y--/root,abhinavmoudgil95/root,krafczyk/root,arch1tect0r/root,evgeny-boger/root,thomaskeck/root,0x0all/ROOT,gbitzes/root,karies/root,omazapa/root,arch1tect0r/root,Duraznos/root,beniz/root,veprbl/root,dfunke/root,zzxuanyuan/root,mattkretz/root,pspe/root,simonpf/root,mkret2/root,simonpf/root,omazapa/root-old,dfunke/root,lgiommi/root,mattkretz/root,mattkretz/root,lgiommi/root,davidlt/root,lgiommi/root,jrtomps/root,buuck/root,CristinaCristescu/root,arch1tect0r/root,root-mirror/root,perovic/root,Y--/root,root-mirror/root,georgtroska/root,gbitzes/root,dfunke/root,karies/root,karies/root,Y--/root,sawenzel/root,georgtroska/root,arch1tect0r/root,0x0all/ROOT,bbockelm/root,karies/root,zzxuanyuan/root,veprbl/root,nilqed/root,agarciamontoro/root,esakellari/root,pspe/root,CristinaCristescu/root,omazapa/root,esakellari/root,omazapa/root-old,mkret2/root,nilqed/root,vukasinmilosevic/root,Y--/root,mhuwiler/rootauto,agarciamontoro/root,BerserkerTroll/root,pspe/root,omazapa/root-old,krafczyk/root,sawenzel/root,krafczyk/root,sbinet/cxx-root,esakellari/my_root_for_test,olifre/root,thomaskeck/root,mkret2/root,smarinac/root,sbinet/cxx-root,zzxuanyuan/root,gbitzes/root,Duraznos/root,zzxuanyuan/root-compressor-dummy,beniz/root,thomaskeck/root,gganis/root,abhinavmoudgil95/root,zzxuanyuan/root,root-mirror/root,agarciamontoro/root,gganis/root,sbinet/cxx-root,gganis/root,zzxuanyuan/root-compressor-dummy,evgeny-boger/root,sirinath/root,veprbl/root,perovic/root,BerserkerTroll/root,zzxuanyuan/root-compressor-dummy,sbinet/cxx-root,buuck/root,abhinavmoudgil95/root,0x0all/ROOT,satyarth934/root,davidlt/root,evgeny-boger/root,bbockelm/root,esakellari/root,veprbl/root,arch1tect0r/root,mattkretz/root,bbockelm/root,mhuwiler/rootauto,evgeny-boger/root,Duraznos/root,mhuwiler/rootauto,omazapa/root-old,beniz/root,simonpf/root,agarciamontoro/root,pspe/root,mhuwiler/rootauto,0x0all/ROOT,jrtomps/root,gbitzes/root,krafczyk/root,thomaskeck/root,satyarth934/root,nilqed/root,zzxuanyuan/root-compressor-dummy,georgtroska/root,gganis/root,buuck/root,root-mirror/root,smarinac/root,zzxuanyuan/root-compressor-dummy,mkret2/root,Duraznos/root,bbockelm/root,karies/root,zzxuanyuan/root-compressor-dummy,zzxuanyuan/root,sawenzel/root,mhuwiler/rootauto,lgiommi/root,Y--/root,zzxuanyuan/root-compressor-dummy,Y--/root,omazapa/root-old,satyarth934/root,karies/root,Duraznos/root,omazapa/root,sawenzel/root,nilqed/root,karies/root,Y--/root,CristinaCristescu/root,dfunke/root,BerserkerTroll/root,nilqed/root,esakellari/root,Duraznos/root,BerserkerTroll/root,omazapa/root,omazapa/root,bbockelm/root,thomaskeck/root,esakellari/my_root_for_test,lgiommi/root,zzxuanyuan/root-compressor-dummy,buuck/root,mattkretz/root,pspe/root,Duraznos/root,veprbl/root,thomaskeck/root,pspe/root,satyarth934/root,sbinet/cxx-root,bbockelm/root,mkret2/root,sbinet/cxx-root,esakellari/root,olifre/root,sawenzel/root,perovic/root,agarciamontoro/root,jrtomps/root,dfunke/root,mkret2/root,arch1tect0r/root,vukasinmilosevic/root,root-mirror/root,smarinac/root,buuck/root,sbinet/cxx-root,dfunke/root,veprbl/root,arch1tect0r/root,simonpf/root,vukasinmilosevic/root,sirinath/root,bbockelm/root,lgiommi/root,abhinavmoudgil95/root,lgiommi/root,root-mirror/root,simonpf/root,root-mirror/root,smarinac/root,sawenzel/root,bbockelm/root,perovic/root,georgtroska/root,omazapa/root-old,arch1tect0r/root,davidlt/root,omazapa/root-old,evgeny-boger/root,esakellari/my_root_for_test,veprbl/root,beniz/root,smarinac/root,perovic/root,sirinath/root,thomaskeck/root,gbitzes/root,olifre/root,CristinaCristescu/root,pspe/root,esakellari/root,perovic/root,thomaskeck/root,zzxuanyuan/root,abhinavmoudgil95/root,mattkretz/root,omazapa/root,sirinath/root,root-mirror/root,nilqed/root,lgiommi/root,zzxuanyuan/root-compressor-dummy,zzxuanyuan/root-compressor-dummy,simonpf/root,omazapa/root,sbinet/cxx-root,davidlt/root,jrtomps/root,gbitzes/root,georgtroska/root,omazapa/root-old,omazapa/root-old,simonpf/root,mattkretz/root,jrtomps/root,dfunke/root,Y--/root,davidlt/root,bbockelm/root,sirinath/root,dfunke/root,krafczyk/root,beniz/root,nilqed/root,beniz/root,satyarth934/root,beniz/root,vukasinmilosevic/root,gganis/root,smarinac/root,Duraznos/root,esakellari/my_root_for_test,krafczyk/root,davidlt/root,agarciamontoro/root,davidlt/root,BerserkerTroll/root,georgtroska/root,esakellari/my_root_for_test,BerserkerTroll/root,veprbl/root,arch1tect0r/root,sawenzel/root,sirinath/root,Y--/root,CristinaCristescu/root,sirinath/root,nilqed/root,perovic/root,BerserkerTroll/root,zzxuanyuan/root-compressor-dummy,bbockelm/root,nilqed/root,davidlt/root,abhinavmoudgil95/root,esakellari/my_root_for_test,olifre/root,omazapa/root-old,perovic/root,vukasinmilosevic/root,karies/root,krafczyk/root,sirinath/root,0x0all/ROOT,mhuwiler/rootauto,zzxuanyuan/root,bbockelm/root,esakellari/root,abhinavmoudgil95/root,sbinet/cxx-root,mkret2/root,esakellari/my_root_for_test,CristinaCristescu/root,beniz/root,krafczyk/root,veprbl/root,esakellari/root,karies/root,agarciamontoro/root,zzxuanyuan/root,jrtomps/root,pspe/root,davidlt/root,0x0all/ROOT,satyarth934/root,gbitzes/root,esakellari/root,simonpf/root,gbitzes/root,mkret2/root,agarciamontoro/root,veprbl/root,smarinac/root,buuck/root,mattkretz/root,evgeny-boger/root,olifre/root,olifre/root,omazapa/root,krafczyk/root,BerserkerTroll/root,mattkretz/root,zzxuanyuan/root,veprbl/root,sbinet/cxx-root,beniz/root,omazapa/root-old,simonpf/root,esakellari/my_root_for_test,omazapa/root,buuck/root,lgiommi/root,CristinaCristescu/root,agarciamontoro/root,sawenzel/root,sirinath/root,BerserkerTroll/root,vukasinmilosevic/root,dfunke/root,abhinavmoudgil95/root,vukasinmilosevic/root,buuck/root,satyarth934/root,root-mirror/root,beniz/root,abhinavmoudgil95/root,olifre/root,olifre/root,thomaskeck/root,smarinac/root,georgtroska/root,BerserkerTroll/root,gganis/root,omazapa/root,satyarth934/root,sawenzel/root,vukasinmilosevic/root,simonpf/root,zzxuanyuan/root,evgeny-boger/root,smarinac/root,zzxuanyuan/root,arch1tect0r/root,karies/root,olifre/root,gganis/root,beniz/root,evgeny-boger/root,root-mirror/root,mhuwiler/rootauto,esakellari/root,CristinaCristescu/root,CristinaCristescu/root,Y--/root,jrtomps/root,mkret2/root,CristinaCristescu/root,0x0all/ROOT,vukasinmilosevic/root,lgiommi/root,gganis/root,0x0all/ROOT,smarinac/root,mattkretz/root,georgtroska/root,sbinet/cxx-root,mkret2/root,buuck/root,0x0all/ROOT,arch1tect0r/root,gbitzes/root,pspe/root,perovic/root,georgtroska/root,jrtomps/root,root-mirror/root,gbitzes/root,agarciamontoro/root,simonpf/root,olifre/root,mhuwiler/rootauto,perovic/root,perovic/root