[Long runtime tests] Link the Objective-C runtime.
[Long runtime tests] Link the Objective-C runtime.

The long-running runtime tests depend on the Objective-C runtime on
Darwin, so link it directly rather than relying on various uses of
__builtin_available to link CoreFoundation for us.

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