Allocate backing memory for empty attributes.
Allocate backing memory for empty attributes.

Empty attributes are borrowed from previous versions.  We need to
guarantee that the references are valid for long enough.

jtk54/HyperDex,tempbottle/HyperDex,cactorium/HyperDex,hyc/HyperDex,rescrv/HyperDex,tempbottle/HyperDex,rescrv/HyperDex,pombredanne/HyperDex,rescrv/HyperDex,pombredanne/HyperDex,vashstorm/HyperDex,vashstorm/HyperDex,tempbottle/HyperDex,cactorium/HyperDex,UIKit0/HyperDex,hyc/HyperDex,cactorium/HyperDex,jtk54/HyperDex,jtk54/HyperDex,jtk54/HyperDex,jtk54/HyperDex,tempbottle/HyperDex,pombredanne/HyperDex,jtk54/HyperDex,vashstorm/HyperDex,pombredanne/HyperDex,cactorium/HyperDex,UIKit0/HyperDex,pombredanne/HyperDex,tempbottle/HyperDex,UIKit0/HyperDex,hyc/HyperDex,cactorium/HyperDex,UIKit0/HyperDex,hyc/HyperDex,vashstorm/HyperDex,hyc/HyperDex,tempbottle/HyperDex,hyc/HyperDex,rescrv/HyperDex,vashstorm/HyperDex,cactorium/HyperDex,tempbottle/HyperDex,rescrv/HyperDex,cactorium/HyperDex,vashstorm/HyperDex,rescrv/HyperDex,hyc/HyperDex,rescrv/HyperDex,UIKit0/HyperDex,cactorium/HyperDex,vashstorm/HyperDex,pombredanne/HyperDex,jtk54/HyperDex,UIKit0/HyperDex,pombredanne/HyperDex,hyc/HyperDex,vashstorm/HyperDex,rescrv/HyperDex,tempbottle/HyperDex,jtk54/HyperDex,vashstorm/HyperDex,cactorium/HyperDex,rescrv/HyperDex,UIKit0/HyperDex,UIKit0/HyperDex,pombredanne/HyperDex,jtk54/HyperDex,UIKit0/HyperDex,tempbottle/HyperDex,pombredanne/HyperDex