Add version of non strong ref prims that uses a closure based approach to access the value.
Add version of non strong ref prims that uses a closure based approach to access the value.

I am going to add a version of this that tests that Unmanaged._withUGR
gives us expected performance. So we really need both versions of all of
the four current benchmarks to make this truly fair.

stephentyrone/swift,JGiola/swift,allevato/swift,roambotics/swift,roambotics/swift,allevato/swift,tkremenek/swift,apple/swift,hooman/swift,rudkx/swift,hooman/swift,jckarter/swift,glessard/swift,glessard/swift,tkremenek/swift,allevato/swift,allevato/swift,aschwaighofer/swift,parkera/swift,harlanhaskins/swift,JGiola/swift,nathawes/swift,stephentyrone/swift,jmgc/swift,jmgc/swift,benlangmuir/swift,atrick/swift,roambotics/swift,glessard/swift,harlanhaskins/swift,nathawes/swift,nathawes/swift,benlangmuir/swift,jmgc/swift,aschwaighofer/swift,ahoppen/swift,xwu/swift,apple/swift,benlangmuir/swift,parkera/swift,roambotics/swift,jckarter/swift,CodaFi/swift,parkera/swift,xwu/swift,xwu/swift,aschwaighofer/swift,apple/swift,CodaFi/swift,hooman/swift,benlangmuir/swift,parkera/swift,hooman/swift,jckarter/swift,gregomni/swift,nathawes/swift,stephentyrone/swift,gregomni/swift,CodaFi/swift,tkremenek/swift,CodaFi/swift,stephentyrone/swift,xwu/swift,jckarter/swift,parkera/swift,benlangmuir/swift,harlanhaskins/swift,ahoppen/swift,allevato/swift,jckarter/swift,aschwaighofer/swift,ahoppen/swift,jmgc/swift,ahoppen/swift,stephentyrone/swift,tkremenek/swift,parkera/swift,parkera/swift,JGiola/swift,jckarter/swift,CodaFi/swift,benlangmuir/swift,xwu/swift,airspeedswift/swift,hooman/swift,jmgc/swift,xwu/swift,JGiola/swift,rudkx/swift,atrick/swift,jckarter/swift,atrick/swift,glessard/swift,airspeedswift/swift,gregomni/swift,gregomni/swift,apple/swift,JGiola/swift,tkremenek/swift,gregomni/swift,rudkx/swift,airspeedswift/swift,apple/swift,jmgc/swift,xwu/swift,glessard/swift,atrick/swift,allevato/swift,roambotics/swift,airspeedswift/swift,aschwaighofer/swift,jmgc/swift,nathawes/swift,airspeedswift/swift,atrick/swift,harlanhaskins/swift,roambotics/swift,nathawes/swift,harlanhaskins/swift,harlanhaskins/swift,ahoppen/swift,ahoppen/swift,atrick/swift,airspeedswift/swift,JGiola/swift,glessard/swift,hooman/swift,harlanhaskins/swift,rudkx/swift,hooman/swift,aschwaighofer/swift,tkremenek/swift,aschwaighofer/swift,stephentyrone/swift,CodaFi/swift,rudkx/swift,gregomni/swift,rudkx/swift,tkremenek/swift,parkera/swift,apple/swift,stephentyrone/swift,airspeedswift/swift,CodaFi/swift,allevato/swift,nathawes/swift