Runtime: Provide a specialization for zero-witness-table existential container layout.
Runtime: Provide a specialization for zero-witness-table existential container layout.

So compilers don't complain about nonstandard use of zero-sized arrays.

Swift SVN r9797

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