Fix findTransitiveGuaranteedUses to only record leaf uses.
Fix findTransitiveGuaranteedUses to only record leaf uses.

Recording uses is now optional. This utility is also used simply to
check for PointerEscape. When uses are recorded, they are used to
extend a live range. There could be a large number of transitive uses
that we don't want to pass back to the caller.

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