[Runtime] Avoid +class overrides when initializing an ObjC class.
[Runtime] Avoid +class overrides when initializing an ObjC class.

swift_getInitializedObjCClass called [c class] to trigger class initialization, and returned the value. This wreaked havoc when the class in question overrides +class. Instead, ignore the return value and return c. Switch from +class to +self, which is much less likely to be overridden. Calling an overridden method could have performance downsides or even cause unwanted side effects.

rdar://problem/49853091
sschiau/swift,nathawes/swift,gribozavr/swift,karwa/swift,gribozavr/swift,sschiau/swift,apple/swift,lorentey/swift,shahmishal/swift,tkremenek/swift,parkera/swift,ahoppen/swift,karwa/swift,nathawes/swift,rudkx/swift,atrick/swift,stephentyrone/swift,aschwaighofer/swift,aschwaighofer/swift,gribozavr/swift,allevato/swift,apple/swift,shahmishal/swift,jmgc/swift,tkremenek/swift,stephentyrone/swift,apple/swift,benlangmuir/swift,CodaFi/swift,parkera/swift,shajrawi/swift,shajrawi/swift,devincoughlin/swift,airspeedswift/swift,devincoughlin/swift,glessard/swift,gregomni/swift,shahmishal/swift,glessard/swift,lorentey/swift,JGiola/swift,tkremenek/swift,nathawes/swift,karwa/swift,harlanhaskins/swift,jckarter/swift,glessard/swift,shajrawi/swift,jmgc/swift,ahoppen/swift,CodaFi/swift,xwu/swift,roambotics/swift,devincoughlin/swift,gribozavr/swift,sschiau/swift,hooman/swift,jckarter/swift,stephentyrone/swift,jmgc/swift,glessard/swift,jckarter/swift,JGiola/swift,nathawes/swift,parkera/swift,CodaFi/swift,hooman/swift,shahmishal/swift,allevato/swift,gribozavr/swift,karwa/swift,parkera/swift,sschiau/swift,aschwaighofer/swift,benlangmuir/swift,gribozavr/swift,sschiau/swift,xedin/swift,tkremenek/swift,lorentey/swift,allevato/swift,hooman/swift,jmgc/swift,gregomni/swift,rudkx/swift,harlanhaskins/swift,lorentey/swift,harlanhaskins/swift,shahmishal/swift,harlanhaskins/swift,atrick/swift,airspeedswift/swift,CodaFi/swift,tkremenek/swift,airspeedswift/swift,devincoughlin/swift,karwa/swift,benlangmuir/swift,benlangmuir/swift,sschiau/swift,CodaFi/swift,apple/swift,xwu/swift,apple/swift,gribozavr/swift,roambotics/swift,gregomni/swift,jckarter/swift,devincoughlin/swift,benlangmuir/swift,xwu/swift,ahoppen/swift,nathawes/swift,tkremenek/swift,benlangmuir/swift,JGiola/swift,rudkx/swift,shahmishal/swift,gregomni/swift,airspeedswift/swift,jmgc/swift,atrick/swift,allevato/swift,aschwaighofer/swift,hooman/swift,xwu/swift,aschwaighofer/swift,devincoughlin/swift,karwa/swift,jmgc/swift,shajrawi/swift,aschwaighofer/swift,stephentyrone/swift,CodaFi/swift,shajrawi/swift,gribozavr/swift,shajrawi/swift,allevato/swift,ahoppen/swift,devincoughlin/swift,devincoughlin/swift,roambotics/swift,xwu/swift,glessard/swift,jckarter/swift,roambotics/swift,CodaFi/swift,xedin/swift,allevato/swift,ahoppen/swift,sschiau/swift,aschwaighofer/swift,xedin/swift,nathawes/swift,karwa/swift,lorentey/swift,jckarter/swift,atrick/swift,JGiola/swift,JGiola/swift,sschiau/swift,gregomni/swift,harlanhaskins/swift,stephentyrone/swift,hooman/swift,xwu/swift,hooman/swift,harlanhaskins/swift,ahoppen/swift,shajrawi/swift,airspeedswift/swift,hooman/swift,lorentey/swift,atrick/swift,parkera/swift,xedin/swift,stephentyrone/swift,roambotics/swift,lorentey/swift,JGiola/swift,gregomni/swift,shahmishal/swift,lorentey/swift,atrick/swift,apple/swift,karwa/swift,shahmishal/swift,parkera/swift,parkera/swift,xedin/swift,airspeedswift/swift,jmgc/swift,rudkx/swift,glessard/swift,jckarter/swift,parkera/swift,xwu/swift,xedin/swift,xedin/swift,rudkx/swift,stephentyrone/swift,nathawes/swift,roambotics/swift,xedin/swift,airspeedswift/swift,rudkx/swift,shajrawi/swift,allevato/swift,tkremenek/swift,harlanhaskins/swift