use thread_local instead of ThreadLocal for some statics in Random
use thread_local instead of ThreadLocal for some statics in Random

Summary: Exit synchronization is the worst!  The worst!

Reviewed By: @​bmaurer

Differential Revision: D2253073

gavioto/folly,gaoyingie/folly,PPC64/folly,clearlylin/folly,fw1121/folly,Eagle-X/folly,charsyam/folly,stonegithubs/folly,Eagle-X/folly,PoisonBOx/folly,loversInJapan/folly,gaoyingie/folly,juniway/folly,renyinew/folly,arg0/folly,KSreeHarsha/folly,gavioto/folly,SeanRBurton/folly,floxard/folly,stonegithubs/folly,brunomorishita/folly,loversInJapan/folly,Hincoin/folly,PoisonBOx/folly,rklabs/folly,bikong2/folly,theiver9827/folly,brunomorishita/folly,Orvid/folly,charsyam/folly,rklabs/folly,alexst07/folly,gaoyingie/folly,SeanRBurton/folly,theiver9827/folly,fw1121/folly,rklabs/folly,bobegir/folly,clearlylin/folly,arg0/folly,Hincoin/folly,Orvid/folly,floxard/folly,charsyam/folly,PoisonBOx/folly,alexst07/folly,floxard/folly,leolujuyi/folly,floxard/folly,fw1121/folly,alexst07/folly,SeanRBurton/folly,hongliangzhao/folly,upsoft/folly,gavioto/folly,gavioto/folly,KSreeHarsha/folly,lifei/folly,floxard/folly,sonnyhu/folly,SeanRBurton/folly,sonnyhu/folly,bikong2/folly,mqeizi/folly,arg0/folly,mqeizi/folly,lifei/folly,Orvid/folly,leolujuyi/folly,facebook/folly,charsyam/folly,loversInJapan/folly,theiver9827/folly,Eagle-X/folly,mqeizi/folly,gavioto/folly,bobegir/folly,PoisonBOx/folly,lifei/folly,fw1121/folly,bobegir/folly,sonnyhu/folly,bikong2/folly,hongliangzhao/folly,stonegithubs/folly,clearlylin/folly,renyinew/folly,juniway/folly,Eagle-X/folly,PoisonBOx/folly,leolujuyi/folly,PPC64/folly,facebook/folly,PPC64/folly,renyinew/folly,juniway/folly,sonnyhu/folly,gaoyingie/folly,rklabs/folly,arg0/folly,stonegithubs/folly,Orvid/folly,lifei/folly,PPC64/folly,bikong2/folly,KSreeHarsha/folly,Orvid/folly,gaoyingie/folly,brunomorishita/folly,alexst07/folly,hongliangzhao/folly,leolujuyi/folly,fw1121/folly,loversInJapan/folly,mqeizi/folly,alexst07/folly,renyinew/folly,hongliangzhao/folly,SeanRBurton/folly,Hincoin/folly,sonnyhu/folly,Eagle-X/folly,upsoft/folly,KSreeHarsha/folly,upsoft/folly,lifei/folly,rklabs/folly,brunomorishita/folly,upsoft/folly,facebook/folly,bikong2/folly,brunomorishita/folly,Hincoin/folly,juniway/folly,mqeizi/folly,leolujuyi/folly,bobegir/folly,facebook/folly,arg0/folly,theiver9827/folly,juniway/folly,upsoft/folly,hongliangzhao/folly,loversInJapan/folly,theiver9827/folly,Hincoin/folly,clearlylin/folly,clearlylin/folly,stonegithubs/folly,bobegir/folly,KSreeHarsha/folly,facebook/folly,PPC64/folly,renyinew/folly