Fix an infinite loop in the SIL verifier.
Fix an infinite loop in the SIL verifier.

This was an obvious thinko that must not have been hit yet in practice.

hooman/swift,benlangmuir/swift,benlangmuir/swift,glessard/swift,gregomni/swift,tkremenek/swift,roambotics/swift,hooman/swift,xwu/swift,xwu/swift,parkera/swift,rudkx/swift,glessard/swift,JGiola/swift,xwu/swift,gregomni/swift,roambotics/swift,benlangmuir/swift,tkremenek/swift,xwu/swift,roambotics/swift,hooman/swift,tkremenek/swift,apple/swift,JGiola/swift,hooman/swift,parkera/swift,ahoppen/swift,xwu/swift,parkera/swift,atrick/swift,ahoppen/swift,glessard/swift,parkera/swift,rudkx/swift,atrick/swift,JGiola/swift,rudkx/swift,gregomni/swift,rudkx/swift,ahoppen/swift,atrick/swift,atrick/swift,ahoppen/swift,ahoppen/swift,tkremenek/swift,apple/swift,apple/swift,xwu/swift,atrick/swift,JGiola/swift,glessard/swift,parkera/swift,parkera/swift,roambotics/swift,benlangmuir/swift,atrick/swift,rudkx/swift,tkremenek/swift,parkera/swift,apple/swift,rudkx/swift,glessard/swift,xwu/swift,apple/swift,ahoppen/swift,hooman/swift,gregomni/swift,glessard/swift,tkremenek/swift,parkera/swift,benlangmuir/swift,hooman/swift,benlangmuir/swift,roambotics/swift,tkremenek/swift,JGiola/swift,JGiola/swift,gregomni/swift,apple/swift,gregomni/swift,roambotics/swift,hooman/swift