Consistently use list(APPEND for adding linker arguments
Consistently use list(APPEND for adding linker arguments

The Xlinker flags were getting globbed into a single string since
we started adding current/compatibility version arguments to the
linker.

rdar://problem/24622276

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