Add --git-dir option to git for out of source build. Fixes ROOT-5127.
Add --git-dir option to git for out of source build. Fixes ROOT-5127.

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