[deserialization] When linking functions, return failure if we get back a declaration.
[deserialization] When linking functions, return failure if we get back a declaration.

We consider linking to only succeed if we actually convert a declaration
into a definition.

Swift SVN r15070

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