For unix be satisfied with the 16-bit depth buffer -- revert from previous change.
For unix be satisfied with the 16-bit depth buffer -- revert from previous
change.

This is required for:
1. Some virtual machines (VirtualBox at least);
2. On windows when using Xming-mesa and doing ssh to RHEL5 machines.


git-svn-id: acec3fd5b7ea1eb9e79d6329d318e8118ee2e14f@39433 27541ba8-7e3a-0410-8455-c3a389f83636

bbockelm/root,nilqed/root,root-mirror/root,gganis/root,zzxuanyuan/root,esakellari/root,abhinavmoudgil95/root,tc3t/qoot,davidlt/root,cxx-hep/root-cern,thomaskeck/root,karies/root,krafczyk/root,vukasinmilosevic/root,pspe/root,lgiommi/root,karies/root,Dr15Jones/root,abhinavmoudgil95/root,evgeny-boger/root,kirbyherm/root-r-tools,sbinet/cxx-root,karies/root,krafczyk/root,kirbyherm/root-r-tools,esakellari/my_root_for_test,esakellari/root,thomaskeck/root,mhuwiler/rootauto,jrtomps/root,agarciamontoro/root,CristinaCristescu/root,root-mirror/root,sawenzel/root,satyarth934/root,vukasinmilosevic/root,georgtroska/root,georgtroska/root,ffurano/root5,BerserkerTroll/root,omazapa/root-old,davidlt/root,zzxuanyuan/root,karies/root,0x0all/ROOT,root-mirror/root,bbockelm/root,dfunke/root,CristinaCristescu/root,agarciamontoro/root,zzxuanyuan/root,dfunke/root,arch1tect0r/root,simonpf/root,krafczyk/root,root-mirror/root,sawenzel/root,mkret2/root,alexschlueter/cern-root,mkret2/root,smarinac/root,smarinac/root,agarciamontoro/root,dfunke/root,krafczyk/root,0x0all/ROOT,ffurano/root5,simonpf/root,buuck/root,veprbl/root,BerserkerTroll/root,nilqed/root,perovic/root,olifre/root,zzxuanyuan/root,esakellari/root,agarciamontoro/root,root-mirror/root,omazapa/root,Y--/root,Dr15Jones/root,sirinath/root,dfunke/root,thomaskeck/root,jrtomps/root,sirinath/root,esakellari/root,Y--/root,ffurano/root5,bbockelm/root,sawenzel/root,krafczyk/root,sbinet/cxx-root,mhuwiler/rootauto,mkret2/root,tc3t/qoot,sirinath/root,lgiommi/root,gganis/root,zzxuanyuan/root,cxx-hep/root-cern,perovic/root,root-mirror/root,evgeny-boger/root,esakellari/my_root_for_test,arch1tect0r/root,mkret2/root,sbinet/cxx-root,veprbl/root,arch1tect0r/root,tc3t/qoot,Duraznos/root,olifre/root,bbockelm/root,jrtomps/root,BerserkerTroll/root,omazapa/root,krafczyk/root,zzxuanyuan/root,dfunke/root,CristinaCristescu/root,simonpf/root,thomaskeck/root,davidlt/root,agarciamontoro/root,strykejern/TTreeReader,omazapa/root-old,arch1tect0r/root,davidlt/root,satyarth934/root,0x0all/ROOT,simonpf/root,gbitzes/root,alexschlueter/cern-root,nilqed/root,veprbl/root,kirbyherm/root-r-tools,cxx-hep/root-cern,evgeny-boger/root,gbitzes/root,mhuwiler/rootauto,sawenzel/root,georgtroska/root,olifre/root,zzxuanyuan/root,beniz/root,gganis/root,vukasinmilosevic/root,veprbl/root,mattkretz/root,karies/root,sirinath/root,omazapa/root-old,buuck/root,olifre/root,sirinath/root,davidlt/root,Y--/root,thomaskeck/root,cxx-hep/root-cern,BerserkerTroll/root,strykejern/TTreeReader,buuck/root,perovic/root,Y--/root,esakellari/root,agarciamontoro/root,zzxuanyuan/root-compressor-dummy,sawenzel/root,olifre/root,mhuwiler/rootauto,sawenzel/root,gbitzes/root,lgiommi/root,mkret2/root,agarciamontoro/root,sawenzel/root,evgeny-boger/root,mkret2/root,gbitzes/root,dfunke/root,mkret2/root,alexschlueter/cern-root,krafczyk/root,buuck/root,zzxuanyuan/root-compressor-dummy,veprbl/root,Duraznos/root,lgiommi/root,satyarth934/root,strykejern/TTreeReader,CristinaCristescu/root,sawenzel/root,kirbyherm/root-r-tools,sbinet/cxx-root,zzxuanyuan/root-compressor-dummy,ffurano/root5,Duraznos/root,esakellari/my_root_for_test,bbockelm/root,nilqed/root,Duraznos/root,CristinaCristescu/root,zzxuanyuan/root,evgeny-boger/root,satyarth934/root,georgtroska/root,karies/root,sirinath/root,cxx-hep/root-cern,gganis/root,veprbl/root,veprbl/root,mattkretz/root,perovic/root,root-mirror/root,zzxuanyuan/root-compressor-dummy,sbinet/cxx-root,olifre/root,mattkretz/root,mattkretz/root,abhinavmoudgil95/root,omazapa/root-old,buuck/root,CristinaCristescu/root,sbinet/cxx-root,kirbyherm/root-r-tools,satyarth934/root,satyarth934/root,simonpf/root,mattkretz/root,Dr15Jones/root,sirinath/root,pspe/root,davidlt/root,tc3t/qoot,krafczyk/root,georgtroska/root,root-mirror/root,gbitzes/root,arch1tect0r/root,olifre/root,mattkretz/root,abhinavmoudgil95/root,ffurano/root5,Dr15Jones/root,smarinac/root,omazapa/root,bbockelm/root,simonpf/root,evgeny-boger/root,dfunke/root,CristinaCristescu/root,esakellari/my_root_for_test,omazapa/root-old,mattkretz/root,mkret2/root,gbitzes/root,esakellari/my_root_for_test,gganis/root,beniz/root,smarinac/root,zzxuanyuan/root-compressor-dummy,pspe/root,zzxuanyuan/root,gbitzes/root,beniz/root,tc3t/qoot,esakellari/my_root_for_test,kirbyherm/root-r-tools,sawenzel/root,zzxuanyuan/root-compressor-dummy,satyarth934/root,Dr15Jones/root,0x0all/ROOT,vukasinmilosevic/root,zzxuanyuan/root,georgtroska/root,simonpf/root,jrtomps/root,cxx-hep/root-cern,buuck/root,gbitzes/root,arch1tect0r/root,jrtomps/root,smarinac/root,sirinath/root,sirinath/root,mkret2/root,georgtroska/root,abhinavmoudgil95/root,bbockelm/root,evgeny-boger/root,Duraznos/root,dfunke/root,gbitzes/root,sirinath/root,BerserkerTroll/root,sbinet/cxx-root,krafczyk/root,arch1tect0r/root,BerserkerTroll/root,pspe/root,simonpf/root,alexschlueter/cern-root,BerserkerTroll/root,kirbyherm/root-r-tools,davidlt/root,beniz/root,smarinac/root,mhuwiler/rootauto,olifre/root,0x0all/ROOT,georgtroska/root,davidlt/root,cxx-hep/root-cern,simonpf/root,sbinet/cxx-root,olifre/root,krafczyk/root,esakellari/root,esakellari/my_root_for_test,bbockelm/root,tc3t/qoot,pspe/root,simonpf/root,abhinavmoudgil95/root,smarinac/root,buuck/root,olifre/root,zzxuanyuan/root-compressor-dummy,mhuwiler/rootauto,esakellari/root,satyarth934/root,thomaskeck/root,Y--/root,omazapa/root-old,nilqed/root,jrtomps/root,pspe/root,0x0all/ROOT,omazapa/root,davidlt/root,perovic/root,tc3t/qoot,perovic/root,agarciamontoro/root,agarciamontoro/root,bbockelm/root,vukasinmilosevic/root,omazapa/root-old,perovic/root,Dr15Jones/root,veprbl/root,davidlt/root,nilqed/root,strykejern/TTreeReader,lgiommi/root,esakellari/my_root_for_test,gganis/root,perovic/root,BerserkerTroll/root,Y--/root,gganis/root,mhuwiler/rootauto,satyarth934/root,nilqed/root,beniz/root,georgtroska/root,abhinavmoudgil95/root,zzxuanyuan/root-compressor-dummy,root-mirror/root,evgeny-boger/root,alexschlueter/cern-root,sawenzel/root,jrtomps/root,arch1tect0r/root,perovic/root,pspe/root,jrtomps/root,gbitzes/root,lgiommi/root,Dr15Jones/root,abhinavmoudgil95/root,root-mirror/root,lgiommi/root,zzxuanyuan/root,gbitzes/root,arch1tect0r/root,Y--/root,abhinavmoudgil95/root,smarinac/root,Y--/root,buuck/root,evgeny-boger/root,BerserkerTroll/root,mhuwiler/rootauto,gganis/root,Y--/root,arch1tect0r/root,sbinet/cxx-root,nilqed/root,karies/root,omazapa/root,omazapa/root,omazapa/root,buuck/root,abhinavmoudgil95/root,thomaskeck/root,veprbl/root,jrtomps/root,strykejern/TTreeReader,omazapa/root-old,krafczyk/root,evgeny-boger/root,vukasinmilosevic/root,sbinet/cxx-root,evgeny-boger/root,strykejern/TTreeReader,Duraznos/root,omazapa/root-old,omazapa/root,ffurano/root5,0x0all/ROOT,0x0all/ROOT,vukasinmilosevic/root,Y--/root,jrtomps/root,karies/root,mkret2/root,buuck/root,tc3t/qoot,alexschlueter/cern-root,karies/root,bbockelm/root,bbockelm/root,omazapa/root,zzxuanyuan/root,lgiommi/root,Duraznos/root,CristinaCristescu/root,satyarth934/root,0x0all/ROOT,BerserkerTroll/root,veprbl/root,esakellari/root,lgiommi/root,CristinaCristescu/root,arch1tect0r/root,omazapa/root,gganis/root,esakellari/my_root_for_test,dfunke/root,lgiommi/root,simonpf/root,mhuwiler/rootauto,mattkretz/root,lgiommi/root,dfunke/root,smarinac/root,tc3t/qoot,dfunke/root,davidlt/root,karies/root,mhuwiler/rootauto,georgtroska/root,nilqed/root,zzxuanyuan/root-compressor-dummy,beniz/root,zzxuanyuan/root-compressor-dummy,esakellari/my_root_for_test,zzxuanyuan/root-compressor-dummy,gganis/root,beniz/root,pspe/root,nilqed/root,pspe/root,pspe/root,buuck/root,cxx-hep/root-cern,CristinaCristescu/root,beniz/root,esakellari/root,omazapa/root,sbinet/cxx-root,root-mirror/root,CristinaCristescu/root,georgtroska/root,agarciamontoro/root,alexschlueter/cern-root,pspe/root,omazapa/root-old,karies/root,mattkretz/root,vukasinmilosevic/root,Duraznos/root,Y--/root,sirinath/root,Duraznos/root,beniz/root,esakellari/root,strykejern/TTreeReader,vukasinmilosevic/root,mattkretz/root,mattkretz/root,abhinavmoudgil95/root,esakellari/root,mhuwiler/rootauto,sawenzel/root,smarinac/root,satyarth934/root,tc3t/qoot,mkret2/root,perovic/root,beniz/root,olifre/root,thomaskeck/root,omazapa/root-old,beniz/root,Duraznos/root,ffurano/root5,vukasinmilosevic/root,veprbl/root,agarciamontoro/root,vukasinmilosevic/root,thomaskeck/root,nilqed/root,perovic/root,jrtomps/root,Duraznos/root,BerserkerTroll/root,thomaskeck/root,gganis/root