[CMake] Handle out-of-tree builds
[CMake] Handle out-of-tree builds

In out of tree builds CLANG_TABLEGEN_TARGETS will be empty, and add_dependencies requires at least one argument.

arvedviehweger/swift,manavgabhawala/swift,Jnosh/swift,xedin/swift,nathawes/swift,jopamer/swift,calebd/swift,devincoughlin/swift,hughbe/swift,OscarSwanros/swift,nathawes/swift,djwbrown/swift,kperryua/swift,xwu/swift,xwu/swift,tardieu/swift,hughbe/swift,gregomni/swift,hooman/swift,harlanhaskins/swift,tjw/swift,gmilos/swift,arvedviehweger/swift,harlanhaskins/swift,ahoppen/swift,xwu/swift,parkera/swift,gribozavr/swift,rudkx/swift,deyton/swift,alblue/swift,JGiola/swift,practicalswift/swift,shajrawi/swift,CodaFi/swift,swiftix/swift,glessard/swift,karwa/swift,calebd/swift,sschiau/swift,aschwaighofer/swift,kperryua/swift,JGiola/swift,allevato/swift,xwu/swift,milseman/swift,sschiau/swift,arvedviehweger/swift,bitjammer/swift,gribozavr/swift,zisko/swift,hughbe/swift,parkera/swift,OscarSwanros/swift,glessard/swift,ben-ng/swift,tinysun212/swift-windows,austinzheng/swift,jtbandes/swift,tinysun212/swift-windows,xwu/swift,deyton/swift,atrick/swift,karwa/swift,hughbe/swift,JaSpa/swift,gregomni/swift,sschiau/swift,gribozavr/swift,jopamer/swift,JaSpa/swift,benlangmuir/swift,hooman/swift,ahoppen/swift,gribozavr/swift,djwbrown/swift,alblue/swift,modocache/swift,jopamer/swift,atrick/swift,benlangmuir/swift,djwbrown/swift,harlanhaskins/swift,JaSpa/swift,shajrawi/swift,aschwaighofer/swift,CodaFi/swift,jmgc/swift,OscarSwanros/swift,airspeedswift/swift,uasys/swift,jmgc/swift,Jnosh/swift,swiftix/swift,frootloops/swift,felix91gr/swift,tjw/swift,natecook1000/swift,OscarSwanros/swift,tardieu/swift,danielmartin/swift,tjw/swift,brentdax/swift,shajrawi/swift,zisko/swift,Jnosh/swift,brentdax/swift,tinysun212/swift-windows,glessard/swift,nathawes/swift,benlangmuir/swift,austinzheng/swift,manavgabhawala/swift,return/swift,xedin/swift,jckarter/swift,jmgc/swift,sschiau/swift,xedin/swift,codestergit/swift,stephentyrone/swift,sschiau/swift,amraboelela/swift,gottesmm/swift,manavgabhawala/swift,zisko/swift,devincoughlin/swift,nathawes/swift,tjw/swift,milseman/swift,frootloops/swift,felix91gr/swift,natecook1000/swift,danielmartin/swift,gmilos/swift,apple/swift,gregomni/swift,manavgabhawala/swift,therealbnut/swift,sschiau/swift,hooman/swift,OscarSwanros/swift,huonw/swift,jtbandes/swift,brentdax/swift,xedin/swift,apple/swift,lorentey/swift,ben-ng/swift,OscarSwanros/swift,jckarter/swift,amraboelela/swift,huonw/swift,therealbnut/swift,frootloops/swift,roambotics/swift,ben-ng/swift,deyton/swift,gmilos/swift,xedin/swift,tinysun212/swift-windows,Jnosh/swift,JGiola/swift,nathawes/swift,shahmishal/swift,gribozavr/swift,jckarter/swift,codestergit/swift,milseman/swift,glessard/swift,lorentey/swift,allevato/swift,felix91gr/swift,bitjammer/swift,natecook1000/swift,JaSpa/swift,karwa/swift,karwa/swift,jtbandes/swift,brentdax/swift,shajrawi/swift,tardieu/swift,gmilos/swift,manavgabhawala/swift,bitjammer/swift,benlangmuir/swift,hooman/swift,lorentey/swift,gribozavr/swift,ahoppen/swift,CodaFi/swift,djwbrown/swift,shajrawi/swift,gmilos/swift,apple/swift,bitjammer/swift,zisko/swift,return/swift,uasys/swift,kstaring/swift,kstaring/swift,Jnosh/swift,CodaFi/swift,tjw/swift,natecook1000/swift,alblue/swift,milseman/swift,natecook1000/swift,austinzheng/swift,modocache/swift,CodaFi/swift,arvedviehweger/swift,bitjammer/swift,bitjammer/swift,therealbnut/swift,ahoppen/swift,tkremenek/swift,devincoughlin/swift,djwbrown/swift,stephentyrone/swift,swiftix/swift,alblue/swift,shahmishal/swift,allevato/swift,kperryua/swift,felix91gr/swift,ben-ng/swift,lorentey/swift,xedin/swift,devincoughlin/swift,swiftix/swift,roambotics/swift,tkremenek/swift,tkremenek/swift,huonw/swift,hooman/swift,JaSpa/swift,aschwaighofer/swift,shajrawi/swift,tinysun212/swift-windows,JaSpa/swift,shahmishal/swift,atrick/swift,austinzheng/swift,hughbe/swift,xwu/swift,calebd/swift,airspeedswift/swift,austinzheng/swift,swiftix/swift,sschiau/swift,shajrawi/swift,gmilos/swift,djwbrown/swift,airspeedswift/swift,tkremenek/swift,codestergit/swift,jopamer/swift,practicalswift/swift,felix91gr/swift,shajrawi/swift,deyton/swift,kperryua/swift,airspeedswift/swift,tinysun212/swift-windows,harlanhaskins/swift,frootloops/swift,roambotics/swift,parkera/swift,tjw/swift,shahmishal/swift,frootloops/swift,atrick/swift,zisko/swift,gregomni/swift,brentdax/swift,natecook1000/swift,modocache/swift,kperryua/swift,parkera/swift,gregomni/swift,devincoughlin/swift,jtbandes/swift,apple/swift,return/swift,kstaring/swift,allevato/swift,gottesmm/swift,deyton/swift,jopamer/swift,arvedviehweger/swift,tkremenek/swift,gottesmm/swift,kperryua/swift,jopamer/swift,jmgc/swift,rudkx/swift,frootloops/swift,airspeedswift/swift,milseman/swift,gottesmm/swift,JGiola/swift,karwa/swift,swiftix/swift,parkera/swift,arvedviehweger/swift,practicalswift/swift,gottesmm/swift,rudkx/swift,harlanhaskins/swift,Jnosh/swift,rudkx/swift,jckarter/swift,roambotics/swift,uasys/swift,tinysun212/swift-windows,gribozavr/swift,gmilos/swift,airspeedswift/swift,shahmishal/swift,ben-ng/swift,harlanhaskins/swift,jtbandes/swift,apple/swift,austinzheng/swift,glessard/swift,tardieu/swift,felix91gr/swift,jmgc/swift,kperryua/swift,kstaring/swift,danielmartin/swift,uasys/swift,tjw/swift,kstaring/swift,devincoughlin/swift,huonw/swift,calebd/swift,practicalswift/swift,karwa/swift,jckarter/swift,stephentyrone/swift,hughbe/swift,tardieu/swift,milseman/swift,aschwaighofer/swift,stephentyrone/swift,modocache/swift,jtbandes/swift,airspeedswift/swift,tardieu/swift,lorentey/swift,stephentyrone/swift,uasys/swift,lorentey/swift,amraboelela/swift,jopamer/swift,amraboelela/swift,ben-ng/swift,devincoughlin/swift,CodaFi/swift,therealbnut/swift,xwu/swift,aschwaighofer/swift,stephentyrone/swift,djwbrown/swift,jmgc/swift,stephentyrone/swift,atrick/swift,tardieu/swift,hooman/swift,kstaring/swift,natecook1000/swift,shahmishal/swift,practicalswift/swift,danielmartin/swift,ahoppen/swift,modocache/swift,Jnosh/swift,apple/swift,practicalswift/swift,OscarSwanros/swift,xedin/swift,rudkx/swift,gregomni/swift,swiftix/swift,nathawes/swift,therealbnut/swift,shahmishal/swift,JGiola/swift,glessard/swift,arvedviehweger/swift,codestergit/swift,zisko/swift,rudkx/swift,return/swift,uasys/swift,aschwaighofer/swift,tkremenek/swift,amraboelela/swift,roambotics/swift,calebd/swift,calebd/swift,CodaFi/swift,atrick/swift,manavgabhawala/swift,parkera/swift,JaSpa/swift,jtbandes/swift,huonw/swift,devincoughlin/swift,return/swift,tkremenek/swift,frootloops/swift,allevato/swift,shahmishal/swift,karwa/swift,gottesmm/swift,allevato/swift,kstaring/swift,karwa/swift,danielmartin/swift,alblue/swift,allevato/swift,return/swift,gottesmm/swift,benlangmuir/swift,ben-ng/swift,brentdax/swift,zisko/swift,modocache/swift,aschwaighofer/swift,milseman/swift,danielmartin/swift,bitjammer/swift,amraboelela/swift,modocache/swift,codestergit/swift,jmgc/swift,danielmartin/swift,codestergit/swift,manavgabhawala/swift,lorentey/swift,return/swift,calebd/swift,harlanhaskins/swift,JGiola/swift,brentdax/swift,huonw/swift,hughbe/swift,deyton/swift,uasys/swift,xedin/swift,lorentey/swift,sschiau/swift,ahoppen/swift,alblue/swift,hooman/swift,parkera/swift,jckarter/swift,therealbnut/swift,practicalswift/swift,jckarter/swift,parkera/swift,roambotics/swift,codestergit/swift,practicalswift/swift,huonw/swift,nathawes/swift,amraboelela/swift,gribozavr/swift,benlangmuir/swift,therealbnut/swift,austinzheng/swift,alblue/swift,felix91gr/swift,deyton/swift