[ClangImporter] Handle Clang diagnostics purportedly on line 0.
[ClangImporter] Handle Clang diagnostics purportedly on line 0.

We don't handle a line 0 in Swift, and this led to LLDB crashing. I'm not
actually sure why Clang was emitting an error on line 0, either; the full
location was "<built-in>:0:4" and the error was

  module 'CoreFoundation' found in both '.../CoreFoundation-17XE9QM744UO5.pcm'
  and '.../CoreFoundation-2BVMOFFOYI8X.pcm'

which turned out to be another manifestation of rdar://problem/19817341
(this was an older LLDB build). No test cases because I'm not sure how to
trigger this, especially not since the previous Radar was fixed, but I'll
clone it to track down why Clang is using such an unusual location.

rdar://problem/19951280

Swift SVN r25766

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