Support GroupVarint.h under MSVC
Support GroupVarint.h under MSVC

Summary: MSVC supports the intrinsics used by it without any issue other changes, so just make sure the error doesn't trigger on MSVC.
Closes #252

Reviewed By: @yfeldblum

Differential Revision: D2282942

Pulled By: @sgolemon

tempbottle/folly,shaobz/folly,bowlofstew/folly,juniway/folly,clearlylin/folly,sakishum/folly,rklabs/folly,loversInJapan/folly,gavioto/folly,raphaelamorim/folly,Hincoin/folly,fw1121/folly,CJstar/folly,upsoft/folly,charsyam/folly,theiver9827/folly,tempbottle/folly,chjp2046/folly,arg0/folly,gaoyingie/folly,yangjin-unique/folly,lifei/folly,yangjin-unique/folly,SammyK/folly,lifei/folly,guker/folly,wildinto/folly,theiver9827/folly,PoisonBOx/folly,PPC64/folly,tomhughes/folly,doctaweeks/folly,sonnyhu/folly,arg0/folly,chjp2046/folly,lifei/folly,juniway/folly,renyinew/folly,PPC64/folly,alexst07/folly,doctaweeks/folly,yangjin-unique/folly,PoisonBOx/folly,fw1121/folly,renyinew/folly,hongliangzhao/folly,zhiweicai/folly,floxard/folly,juniway/folly,xzmagic/folly,rklabs/folly,upsoft/folly,tomhughes/folly,SeanRBurton/folly,tomhughes/folly,constantine001/folly,SammyK/folly,bowlofstew/folly,SeanRBurton/folly,CJstar/folly,PPC64/folly,stonegithubs/folly,clearlylin/folly,gavioto/folly,sakishum/folly,loversInJapan/folly,xzmagic/folly,fw1121/folly,mqeizi/folly,floxard/folly,bobegir/folly,lifei/folly,bowlofstew/folly,shaobz/folly,SeanRBurton/folly,KSreeHarsha/folly,stonegithubs/folly,upsoft/folly,guker/folly,bikong2/folly,upsoft/folly,chjp2046/folly,brunomorishita/folly,leolujuyi/folly,Eagle-X/folly,reddit/folly,xzmagic/folly,yangjin-unique/folly,wildinto/folly,bobegir/folly,upsoft/folly,gavioto/folly,Hincoin/folly,charsyam/folly,juniway/folly,shaobz/folly,stonegithubs/folly,raphaelamorim/folly,sonnyhu/folly,alexst07/folly,facebook/folly,SeanRBurton/folly,hongliangzhao/folly,Orvid/folly,Orvid/folly,tempbottle/folly,bobegir/folly,gaoyingie/folly,constantine001/folly,alexst07/folly,bikong2/folly,yangjin-unique/folly,constantine001/folly,tempbottle/folly,renyinew/folly,clearlylin/folly,renyinew/folly,bobegir/folly,loversInJapan/folly,rklabs/folly,chjp2046/folly,shaobz/folly,leolujuyi/folly,mqeizi/folly,doctaweeks/folly,tempbottle/folly,constantine001/folly,stonegithubs/folly,rklabs/folly,CJstar/folly,Eagle-X/folly,chjp2046/folly,arg0/folly,CJstar/folly,arg0/folly,gavioto/folly,floxard/folly,bowlofstew/folly,mqeizi/folly,PPC64/folly,clearlylin/folly,sonnyhu/folly,PoisonBOx/folly,facebook/folly,sonnyhu/folly,sakishum/folly,Hincoin/folly,shaobz/folly,zhiweicai/folly,arg0/folly,facebook/folly,SammyK/folly,sonnyhu/folly,Orvid/folly,wildinto/folly,stonegithubs/folly,Orvid/folly,bikong2/folly,facebook/folly,bobegir/folly,fw1121/folly,juniway/folly,Hincoin/folly,raphaelamorim/folly,bowlofstew/folly,gaoyingie/folly,mqeizi/folly,Orvid/folly,leolujuyi/folly,bikong2/folly,KSreeHarsha/folly,gavioto/folly,SeanRBurton/folly,doctaweeks/folly,clearlylin/folly,brunomorishita/folly,raphaelamorim/folly,KSreeHarsha/folly,zhiweicai/folly,rklabs/folly,guker/folly,KSreeHarsha/folly,PPC64/folly,PoisonBOx/folly,brunomorishita/folly,leolujuyi/folly,tomhughes/folly,loversInJapan/folly,theiver9827/folly,reddit/folly,reddit/folly,xzmagic/folly,reddit/folly,Hincoin/folly,wildinto/folly,loversInJapan/folly,reddit/folly,renyinew/folly,charsyam/folly,hongliangzhao/folly,gaoyingie/folly,PoisonBOx/folly,theiver9827/folly,doctaweeks/folly,alexst07/folly,sakishum/folly,wildinto/folly,KSreeHarsha/folly,zhiweicai/folly,Eagle-X/folly,zhiweicai/folly,constantine001/folly,Eagle-X/folly,fw1121/folly,leolujuyi/folly,brunomorishita/folly,SammyK/folly,gaoyingie/folly,mqeizi/folly,CJstar/folly,theiver9827/folly,hongliangzhao/folly,sakishum/folly,guker/folly,SammyK/folly,lifei/folly,guker/folly,brunomorishita/folly,facebook/folly,raphaelamorim/folly,bikong2/folly,charsyam/folly,hongliangzhao/folly,floxard/folly,xzmagic/folly,Eagle-X/folly,tomhughes/folly,floxard/folly,alexst07/folly