remove get_weak from singleton
remove get_weak from singleton

Summary:

Test Plan: fbmake runtests, OBC no longer segfaults

Reviewed By: mshneer@fb.com

Subscribers: fbcode-common-diffs@, trunkagent, mcduff, marccelani, hitesh, mshneer, njormrod, lins

FB internal diff: D1573880

wildinto/folly,KSreeHarsha/folly,bikong2/folly,sakishum/folly,PPC64/folly,sonnyhu/folly,rklabs/folly,stonegithubs/folly,bobegir/folly,bsampath/folly,tempbottle/folly,mqeizi/folly,renyinew/folly,shaobz/folly,brunomorishita/folly,clearlylin/folly,bobegir/folly,kernelim/folly,cole14/folly,raphaelamorim/folly,leolujuyi/folly,constantine001/folly,KSreeHarsha/folly,Hincoin/folly,yangjin-unique/folly,raphaelamorim/folly,juniway/folly,tomhughes/folly,shaobz/folly,juniway/folly,gaoyingie/folly,sakishum/folly,PPC64/folly,mqeizi/folly,loversInJapan/folly,hongliangzhao/folly,floxard/folly,bsampath/folly,wildinto/folly,charsyam/folly,gavioto/folly,renyinew/folly,SammyK/folly,CJstar/folly,facebook/folly,renyinew/folly,kernelim/folly,fw1121/folly,guker/folly,alexst07/folly,colemancda/folly,xzmagic/folly,lifei/folly,reddit/folly,bowlofstew/folly,PoisonBOx/folly,charsyam/folly,gavioto/folly,yangjin-unique/folly,hongliangzhao/folly,romange/folly,theiver9827/folly,bowlofstew/folly,Eagle-X/folly,gaoyingie/folly,CJstar/folly,yangjin-unique/folly,lifei/folly,Eagle-X/folly,ykarlsbrun/folly,shaobz/folly,nickhen/folly,loverszhaokai/folly,lifei/folly,CJstar/folly,Hincoin/folly,nickhen/folly,sakishum/folly,facebook/folly,floxard/folly,bowlofstew/folly,bobegir/folly,sakishum/folly,nickhen/folly,PoisonBOx/folly,doctaweeks/folly,constantine001/folly,bsampath/folly,upsoft/folly,rklabs/folly,theiver9827/folly,cole14/folly,constantine001/folly,clearlinux/folly,tomhughes/folly,KSreeHarsha/folly,facebook/folly,romange/folly,lifei/folly,bowlofstew/folly,arg0/folly,arg0/folly,SeanRBurton/folly,reddit/folly,Orvid/folly,juniway/folly,loversInJapan/folly,reddit/folly,project-zerus/folly,colemancda/folly,doctaweeks/folly,gavioto/folly,xzmagic/folly,arg0/folly,bikong2/folly,constantine001/folly,fw1121/folly,nickhen/folly,zhiweicai/folly,stonegithubs/folly,mqeizi/folly,reddit/folly,tomhughes/folly,fw1121/folly,Orvid/folly,renyinew/folly,doctaweeks/folly,sonnyhu/folly,ykarlsbrun/folly,PPC64/folly,Orvid/folly,PPC64/folly,stonegithubs/folly,SammyK/folly,yangjin-unique/folly,mqeizi/folly,raphaelamorim/folly,guker/folly,kernelim/folly,project-zerus/folly,ykarlsbrun/folly,clearlylin/folly,clearlinux/folly,loverszhaokai/folly,lifei/folly,cole14/folly,PoisonBOx/folly,SammyK/folly,Eagle-X/folly,bikong2/folly,shaobz/folly,theiver9827/folly,xzmagic/folly,KSreeHarsha/folly,xzmagic/folly,SeanRBurton/folly,tempbottle/folly,zhiweicai/folly,tempbottle/folly,raphaelamorim/folly,doctaweeks/folly,chjp2046/folly,CJstar/folly,wildinto/folly,juniway/folly,chjp2046/folly,brunomorishita/folly,nickhen/folly,theiver9827/folly,KSreeHarsha/folly,arg0/folly,tomhughes/folly,Orvid/folly,colemancda/folly,Eagle-X/folly,sonnyhu/folly,clearlylin/folly,SeanRBurton/folly,leolujuyi/folly,CJstar/folly,cppfool/folly,guker/folly,SammyK/folly,clearlinux/folly,bikong2/folly,upsoft/folly,Hincoin/folly,zhiweicai/folly,cole14/folly,floxard/folly,charsyam/folly,stonegithubs/folly,guker/folly,zhiweicai/folly,hongliangzhao/folly,romange/folly,raphaelamorim/folly,alexst07/folly,doctaweeks/folly,wildinto/folly,sonnyhu/folly,mqeizi/folly,guker/folly,chjp2046/folly,colemancda/folly,clearlylin/folly,loversInJapan/folly,chjp2046/folly,project-zerus/folly,rklabs/folly,upsoft/folly,reddit/folly,cole14/folly,Eagle-X/folly,yangjin-unique/folly,sonnyhu/folly,facebook/folly,bsampath/folly,fw1121/folly,tempbottle/folly,romange/folly,gavioto/folly,PoisonBOx/folly,PoisonBOx/folly,cppfool/folly,gaoyingie/folly,clearlylin/folly,floxard/folly,ykarlsbrun/folly,ykarlsbrun/folly,cppfool/folly,juniway/folly,brunomorishita/folly,kernelim/folly,tomhughes/folly,theiver9827/folly,arg0/folly,kernelim/folly,leolujuyi/folly,bsampath/folly,sakishum/folly,upsoft/folly,loverszhaokai/folly,shaobz/folly,chjp2046/folly,clearlinux/folly,hongliangzhao/folly,loversInJapan/folly,bobegir/folly,bobegir/folly,loverszhaokai/folly,upsoft/folly,colemancda/folly,SammyK/folly,cppfool/folly,leolujuyi/folly,gavioto/folly,romange/folly,renyinew/folly,zhiweicai/folly,brunomorishita/folly,clearlinux/folly,tempbottle/folly,loversInJapan/folly,fw1121/folly,rklabs/folly,gaoyingie/folly,Orvid/folly,hongliangzhao/folly,constantine001/folly,brunomorishita/folly,floxard/folly,rklabs/folly,facebook/folly,leolujuyi/folly,loverszhaokai/folly,project-zerus/folly,gaoyingie/folly,Hincoin/folly,alexst07/folly,cppfool/folly,bowlofstew/folly,alexst07/folly,bikong2/folly,SeanRBurton/folly,SeanRBurton/folly,xzmagic/folly,stonegithubs/folly,charsyam/folly,wildinto/folly,PPC64/folly,Hincoin/folly,project-zerus/folly,alexst07/folly