[Frontend] When setting the MainInputFilename in the compiler invocation, check first that the input filenames vector is not empty.
[Frontend] When setting the MainInputFilename in the compiler invocation, check first that the input filenames vector is not empty.

Swift SVN r11484

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