SILPrinter: split printUsersOfSILNode into printUsersOfValue and printUsersOfInstruction.
SILPrinter: split printUsersOfSILNode into printUsersOfValue and printUsersOfInstruction.

A small cleanup, NFC.

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