Runtime: Add +description and ±_copyDescription to SwiftObject.
Runtime: Add +description and ±_copyDescription to SwiftObject.

+description missing was an oversight. NSError apparently uses the _copyDescription SPI on NSObject to get the description of its userInfo object. Lift the implementation from NSObject, which apparently really retains rather than copies the description. Fixes rdar://problem/19899687.

Swift SVN r25428

tjw/swift,gmilos/swift,MukeshKumarS/Swift,emilstahl/swift,tardieu/swift,jtbandes/swift,frootloops/swift,CodaFi/swift,adrfer/swift,jckarter/swift,xwu/swift,nathawes/swift,bitjammer/swift,felix91gr/swift,airspeedswift/swift,swiftix/swift.old,sdulal/swift,milseman/swift,MukeshKumarS/Swift,tkremenek/swift,cbrentharris/swift,tinysun212/swift-windows,ahoppen/swift,uasys/swift,natecook1000/swift,tardieu/swift,shahmishal/swift,brentdax/swift,LeoShimonaka/swift,return/swift,mightydeveloper/swift,JaSpa/swift,gmilos/swift,ahoppen/swift,rudkx/swift,aschwaighofer/swift,aschwaighofer/swift,shahmishal/swift,glessard/swift,devincoughlin/swift,djwbrown/swift,uasys/swift,KrishMunot/swift,apple/swift,karwa/swift,rudkx/swift,uasys/swift,xwu/swift,parkera/swift,danielmartin/swift,OscarSwanros/swift,calebd/swift,codestergit/swift,benlangmuir/swift,emilstahl/swift,emilstahl/swift,djwbrown/swift,devincoughlin/swift,stephentyrone/swift,austinzheng/swift,JGiola/swift,mightydeveloper/swift,codestergit/swift,Jnosh/swift,uasys/swift,nathawes/swift,ahoppen/swift,alblue/swift,KrishMunot/swift,jopamer/swift,khizkhiz/swift,ken0nek/swift,kstaring/swift,apple/swift,glessard/swift,sdulal/swift,SwiftAndroid/swift,kstaring/swift,lorentey/swift,OscarSwanros/swift,sdulal/swift,IngmarStein/swift,kentya6/swift,parkera/swift,shahmishal/swift,natecook1000/swift,atrick/swift,SwiftAndroid/swift,hooman/swift,harlanhaskins/swift,hughbe/swift,aschwaighofer/swift,jckarter/swift,hooman/swift,milseman/swift,LeoShimonaka/swift,felix91gr/swift,CodaFi/swift,xedin/swift,harlanhaskins/swift,KrishMunot/swift,alblue/swift,modocache/swift,adrfer/swift,cbrentharris/swift,roambotics/swift,milseman/swift,mightydeveloper/swift,Ivacker/swift,codestergit/swift,stephentyrone/swift,modocache/swift,zisko/swift,swiftix/swift.old,lorentey/swift,amraboelela/swift,ken0nek/swift,shajrawi/swift,stephentyrone/swift,mightydeveloper/swift,ben-ng/swift,adrfer/swift,nathawes/swift,OscarSwanros/swift,calebd/swift,Jnosh/swift,amraboelela/swift,SwiftAndroid/swift,tkremenek/swift,danielmartin/swift,cbrentharris/swift,johnno1962d/swift,cbrentharris/swift,airspeedswift/swift,kusl/swift,kusl/swift,frootloops/swift,benlangmuir/swift,gottesmm/swift,nathawes/swift,emilstahl/swift,sdulal/swift,jmgc/swift,gribozavr/swift,Jnosh/swift,tardieu/swift,swiftix/swift,swiftix/swift.old,IngmarStein/swift,kentya6/swift,tinysun212/swift-windows,parkera/swift,khizkhiz/swift,gregomni/swift,devincoughlin/swift,shajrawi/swift,allevato/swift,airspeedswift/swift,lorentey/swift,therealbnut/swift,tjw/swift,manavgabhawala/swift,gribozavr/swift,modocache/swift,MukeshKumarS/Swift,gregomni/swift,sdulal/swift,MukeshKumarS/Swift,arvedviehweger/swift,therealbnut/swift,modocache/swift,kentya6/swift,swiftix/swift,Ivacker/swift,xedin/swift,danielmartin/swift,dduan/swift,tinysun212/swift-windows,amraboelela/swift,kentya6/swift,IngmarStein/swift,adrfer/swift,practicalswift/swift,gmilos/swift,rudkx/swift,gregomni/swift,brentdax/swift,alblue/swift,atrick/swift,brentdax/swift,ben-ng/swift,CodaFi/swift,huonw/swift,ben-ng/swift,parkera/swift,bitjammer/swift,SwiftAndroid/swift,sdulal/swift,Ivacker/swift,modocache/swift,bitjammer/swift,LeoShimonaka/swift,jtbandes/swift,OscarSwanros/swift,hughbe/swift,lorentey/swift,adrfer/swift,frootloops/swift,mightydeveloper/swift,calebd/swift,huonw/swift,ahoppen/swift,tinysun212/swift-windows,sschiau/swift,devincoughlin/swift,danielmartin/swift,manavgabhawala/swift,khizkhiz/swift,alblue/swift,jtbandes/swift,KrishMunot/swift,swiftix/swift,ken0nek/swift,jtbandes/swift,therealbnut/swift,huonw/swift,hooman/swift,jckarter/swift,karwa/swift,dduan/swift,jopamer/swift,tjw/swift,ken0nek/swift,felix91gr/swift,CodaFi/swift,jopamer/swift,practicalswift/swift,johnno1962d/swift,stephentyrone/swift,khizkhiz/swift,harlanhaskins/swift,practicalswift/swift,natecook1000/swift,aschwaighofer/swift,karwa/swift,hughbe/swift,devincoughlin/swift,kusl/swift,cbrentharris/swift,lorentey/swift,zisko/swift,stephentyrone/swift,jckarter/swift,amraboelela/swift,LeoShimonaka/swift,nathawes/swift,practicalswift/swift,benlangmuir/swift,return/swift,swiftix/swift,jtbandes/swift,allevato/swift,MukeshKumarS/Swift,therealbnut/swift,practicalswift/swift,brentdax/swift,austinzheng/swift,russbishop/swift,JaSpa/swift,dduan/swift,gribozavr/swift,milseman/swift,slavapestov/swift,karwa/swift,ben-ng/swift,tjw/swift,deyton/swift,jopamer/swift,johnno1962d/swift,stephentyrone/swift,calebd/swift,slavapestov/swift,manavgabhawala/swift,IngmarStein/swift,gmilos/swift,gribozavr/swift,shajrawi/swift,modocache/swift,shajrawi/swift,johnno1962d/swift,gribozavr/swift,apple/swift,therealbnut/swift,swiftix/swift,ben-ng/swift,xwu/swift,stephentyrone/swift,frootloops/swift,swiftix/swift.old,uasys/swift,IngmarStein/swift,KrishMunot/swift,kperryua/swift,jopamer/swift,arvedviehweger/swift,MukeshKumarS/Swift,russbishop/swift,djwbrown/swift,jckarter/swift,xwu/swift,mightydeveloper/swift,deyton/swift,amraboelela/swift,Jnosh/swift,swiftix/swift.old,Ivacker/swift,slavap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