Fix the hash function for SILDebugScopes to handle the empty scopes generated for artificial LLVM-only functions correctly.
Fix the hash function for SILDebugScopes to handle the empty scopes
generated for artificial LLVM-only functions correctly.

This fixes an IR Verifier error that was introduced in LLVM r302576.
The bug itself was introduced together with the code in 5ea2d13f5e0.

<rdar://problem/31926379>

hooman/swift,allevato/swift,jtbandes/swift,amraboelela/swift,jmgc/swift,gregomni/swift,practicalswift/swift,jopamer/swift,uasys/swift,swiftix/swift,frootloops/swift,jtbandes/swift,benlangmuir/swift,OscarSwanros/swift,return/swift,stephentyrone/swift,JGiola/swift,jckarter/swift,CodaFi/swift,felix91gr/swift,deyton/swift,nathawes/swift,hooman/swift,shahmishal/swift,gribozavr/swift,shajrawi/swift,JGiola/swift,rudkx/swift,karwa/swift,gregomni/swift,swiftix/swift,zisko/swift,gribozavr/swift,djwbrown/swift,alblue/swift,gribozavr/swift,djwbrown/swift,airspeedswift/swift,airspeedswift/swift,brentdax/swift,hooman/swift,karwa/swift,practicalswift/swift,CodaFi/swift,devincoughlin/swift,gribozavr/swift,roambotics/swift,rudkx/swift,shajrawi/swift,Jnosh/swift,OscarSwanros/swift,uasys/swift,xedin/swift,jckarter/swift,jopamer/swift,jtbandes/swift,jckarter/swift,return/swift,aschwaighofer/swift,practicalswift/swift,jtbandes/swift,amraboelela/swift,tkremenek/swift,tjw/swift,danielmartin/swift,austinzheng/swift,stephentyrone/swift,zisko/swift,return/swift,aschwaighofer/swift,huonw/swift,gribozavr/swift,felix91gr/swift,practicalswift/swift,uasys/swift,jtbandes/swift,natecook1000/swift,hughbe/swift,deyton/swift,allevato/swift,lorentey/swift,JGiola/swift,felix91gr/swift,zisko/swift,frootloops/swift,huonw/swift,shahmishal/swift,hooman/swift,amraboelela/swift,lorentey/swift,jmgc/swift,devincoughlin/swift,nathawes/swift,allevato/swift,glessard/swift,calebd/swift,practicalswift/swift,rudkx/swift,amraboelela/swift,devincoughlin/swift,gribozavr/swift,sschiau/swift,glessard/swift,airspeedswift/swift,tkremenek/swift,harlanhaskins/swift,milseman/swift,ahoppen/swift,zisko/swift,devincoughlin/swift,aschwaighofer/swift,jmgc/swift,karwa/swift,CodaFi/swift,rudkx/swift,Jnosh/swift,karwa/swift,xwu/swift,karwa/swift,practicalswift/swift,JGiola/swift,uasys/swift,roambotics/swift,lorentey/swift,shahmishal/swift,return/swift,jopamer/swift,hughbe/swift,lorentey/swift,tjw/swift,jmgc/swift,lorentey/swift,atrick/swift,shahmishal/swift,hughbe/swift,harlanhaskins/swift,danielmartin/swift,jckarter/swift,hooman/swift,frootloops/swift,xedin/swift,huonw/swift,xwu/swift,amraboelela/swift,stephentyrone/swift,allevato/swift,roambotics/swift,jckarter/swift,jmgc/swift,shajrawi/swift,benlangmuir/swift,natecook1000/swift,swiftix/swift,hooman/swift,felix91gr/swift,sschiau/swift,harlanhaskins/swift,deyton/swift,felix91gr/swift,alblue/swift,tjw/swift,jtbandes/swift,jopamer/swift,sschiau/swift,OscarSwanros/swift,JGiola/swift,danielmartin/swift,zisko/swift,harlanhaskins/swift,jmgc/swift,apple/swift,rudkx/swift,gribozavr/swift,apple/swift,nathawes/swift,natecook1000/swift,apple/swift,alblue/swift,huonw/swift,harlanhaskins/swift,nathawes/swift,karwa/swift,nathawes/swift,airspeedswift/swift,tjw/swift,deyton/swift,stephentyrone/swift,djwbrown/swift,aschwaighofer/swift,lorentey/swift,zisko/swift,alblue/swift,swiftix/swift,natecook1000/swift,natecook1000/swift,return/swift,uasys/swift,djwbrown/swift,shajrawi/swift,return/swift,shajrawi/swift,milseman/swift,austinzheng/swift,airspeedswift/swift,jopamer/swift,parkera/swift,aschwaighofer/swift,xedin/swift,Jnosh/swift,danielmartin/swift,deyton/swift,benlangmuir/swift,ahoppen/swift,glessard/swift,brentdax/swift,aschwaighofer/swift,tkremenek/swift,CodaFi/swift,atrick/swift,milseman/swift,austinzheng/swift,alblue/swift,OscarSwanros/swift,tjw/swift,OscarSwanros/swift,practicalswift/swift,milseman/swift,jckarter/swift,calebd/swift,brentdax/swift,allevato/swift,shahmishal/swift,benlangmuir/swift,parkera/swift,allevato/swift,tkremenek/swift,jtbandes/swift,atrick/swift,brentdax/swift,djwbrown/swift,jopamer/swift,benlangmuir/swift,karwa/swift,practicalswift/swift,zisko/swift,return/swift,parkera/swift,uasys/swift,harlanhaskins/swift,hooman/swift,roambotics/swift,parkera/swift,xedin/swift,rudkx/swift,gregomni/swift,devincoughlin/swift,calebd/swift,shahmishal/swift,devincoughlin/swift,frootloops/swift,xwu/swift,xedin/swift,parkera/swift,gregomni/swift,huonw/swift,tjw/swift,xwu/swift,glessard/swift,amraboelela/swift,tjw/swift,deyton/swift,austinzheng/swift,milseman/swift,aschwaighofer/swift,calebd/swift,karwa/swift,devincoughlin/swift,nathawes/swift,frootloops/swift,tkremenek/swift,parkera/swift,CodaFi/swift,Jnosh/swift,atrick/swift,calebd/swift,ahoppen/swift,huonw/swift,gregomni/swift,Jnosh/swift,deyton/swift,sschiau/swift,hughbe/swift,shajrawi/swift,apple/swift,OscarSwanros/swift,atrick/swift,Jnosh/swift,parkera/swift,djwbrown/swift,jmgc/swift,brentdax/swift,parkera/swift,stephentyrone/swift,ahoppen/swift,sschiau/swift,xwu/swift,devincoughlin/swift,shajrawi/swift,milseman/swift,stephentyrone/swift,glessard/swift,apple/swift,sschiau/swift,uasys/swift,lorentey/swift,felix91gr/swift,xedin/swift,danielmartin/swift,natecook1000/swift,gribozavr/swift,lorentey/swift,xedin/swift,hughbe/swift,calebd/swift,CodaFi/swift,hughbe/swift,harlanhaskins/swift,swiftix/swift,sschiau/swift,xedin/swift,airspeedswift/swift,airspeedswift/swift,shahmishal/swift,ahoppen/swift,huonw/swift,allevato/swift,xwu/swift,danielmartin/swift,milseman/swift,atrick/swift,amraboelela/swift,nathawes/swift,calebd/swift,ahoppen/swift,austinzheng/swift,xwu/swift,CodaFi/swift,benlangmuir/swift,roambotics/swift,tkremenek/swift,frootloops/swift,stephentyrone/swift,tkremenek/swift,brentdax/swift,roambotics/swift,brentdax/swift,danielmartin/swift,apple/swift,sschiau/swift,djwbrown/swift,shajrawi/swift,shahmishal/swift,Jnosh/swift,austinzheng/swift,gregomni/swift,austinzheng/swift,alblue/swift,jopamer/swift,OscarSwanros/swift,glessard/swift,JGiola/swift,jckarter/swift,swiftix/swift,felix91gr/swift,frootloops/swift,natecook1000/swift,alblue/swift,swiftix/swift,hughbe/swift