[CMake] Teach unit tests to handle Release LLVM / Debug Swift.
[CMake] Teach unit tests to handle Release LLVM / Debug Swift.

(and similar mixed modes)

This is duplicating some of the work in swift_llvm_config, and should
probably be refactored back there at some point, but for now this gets
unit tests building in Xcode when the build configurations for LLVM and
Swift aren't the same.

Swift SVN r24257

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