[validation-test] Add line-directive doctests
[validation-test] Add line-directive doctests

`utils/line-directive` is used when building Swift (see
`cmake/modules/AddSwift.cmake`), and includes some doctests. In order
to make sure it continues to behave as intended, add its tests to
`validation-test`.

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