Allow conversion from StringPiece to StringPiece
Allow conversion from StringPiece to StringPiece

Summary: Allow conversion from folly::StringPiece to folly::StringPiece

Test Plan: - fbconfig -r folly && fbmake runtests

Reviewed By: mpawlowski@fb.com

Subscribers: folly-diffs@

FB internal diff: D1752609

Signature: t1:1752609:1419037172:04846f658901306b53fb60c9eafbdf0f4d4d7005

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