Compatibility50: Backport objc_getClass hook patch.
Compatibility50: Backport objc_getClass hook patch.

We don't want older runtimes trying to chase rogue symbolic references through objc_getClass
either. rdar://problem/55036306

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