[windows] Fix handling of Network Service username.
[windows] Fix handling of Network Service username.

In Windows Server 2016 at least, the Network Service user (the one being
used by the CI machine) is returned as Host$, which icacls doesn't
understand. Turn the name into something that icacls if we get a name
that ends with a dollar.

devincoughlin/swift,roambotics/swift,gribozavr/swift,nathawes/swift,lorentey/swift,airspeedswift/swift,JGiola/swift,roambotics/swift,atrick/swift,roambotics/swift,apple/swift,glessard/swift,harlanhaskins/swift,xedin/swift,CodaFi/swift,rudkx/swift,devincoughlin/swift,devincoughlin/swift,harlanhaskins/swift,jmgc/swift,atrick/swift,xwu/swift,xedin/swift,rudkx/swift,hooman/swift,allevato/swift,gribozavr/swift,parkera/swift,airspeedswift/swift,tkremenek/swift,airspeedswift/swift,benlangmuir/swift,roambotics/swift,devincoughlin/swift,shahmishal/swift,shahmishal/swift,lorentey/swift,sschiau/swift,allevato/swift,harlanhaskins/swift,gregomni/swift,roambotics/swift,jckarter/swift,shajrawi/swift,aschwaighofer/swift,CodaFi/swift,glessard/swift,jmgc/swift,karwa/swift,shahmishal/swift,lorentey/swift,parkera/swift,tkremenek/swift,xedin/swift,glessard/swift,gribozavr/swift,harlanhaskins/swift,CodaFi/swift,hooman/swift,xwu/swift,gribozavr/swift,karwa/swift,apple/swift,roambotics/swift,benlangmuir/swift,hooman/swift,glessard/swift,benlangmuir/swift,shahmishal/swift,rudkx/swift,harlanhaskins/swift,xedin/swift,JGiola/swift,gregomni/swift,CodaFi/swift,gribozavr/swift,nathawes/swift,gribozavr/swift,hooman/swift,shahmishal/swift,glessard/swift,shahmishal/swift,apple/swift,jckarter/swift,gribozavr/swift,JGiola/swift,devincoughlin/swift,CodaFi/swift,ahoppen/swift,allevato/swift,shajrawi/swift,sschiau/swift,aschwaighofer/swift,allevato/swift,atrick/swift,atrick/swift,karwa/swift,gregomni/swift,xedin/swift,airspeedswift/swift,allevato/swift,jmgc/swift,hooman/swift,harlanhaskins/swift,sschiau/swift,sschiau/swift,benlangmuir/swift,jmgc/swift,CodaFi/swift,sschiau/swift,karwa/swift,rudkx/swift,xedin/swift,ahoppen/swift,rudkx/swift,parkera/swift,shahmishal/swift,airspeedswift/swift,xwu/swift,karwa/swift,glessard/swift,stephentyrone/swift,aschwaighofer/swift,xedin/swift,devincoughlin/swift,shajrawi/swift,parkera/swift,apple/swift,xwu/swift,nathawes/swift,shajrawi/swift,xedin/swift,atrick/swift,harlanhaskins/swift,sschiau/swift,benlangmuir/swift,jckarter/swift,jckarter/swift,jmgc/swift,stephentyrone/swift,allevato/swift,jckarter/swift,gribozavr/swift,apple/swift,ahoppen/swift,ahoppen/swift,shahmishal/swift,stephentyrone/swift,jckarter/swift,lorentey/swift,parkera/swift,jckarter/swift,aschwaighofer/swift,rudkx/swift,xwu/swift,aschwaighofer/swift,sschiau/swift,lorentey/swift,gregomni/swift,allevato/swift,benlangmuir/swift,shajrawi/swift,nathawes/swift,stephentyrone/swift,aschwaighofer/swift,jmgc/swift,devincoughlin/swift,tkremenek/swift,JGiola/swift,devincoughlin/swift,shajrawi/swift,aschwaighofer/swift,gregomni/swift,sschiau/swift,stephentyrone/swift,parkera/swift,karwa/swift,gregomni/swift,karwa/swift,tkremenek/swift,tkremenek/swift,shajrawi/swift,JGiola/swift,xwu/swift,JGiola/swift,atrick/swift,tkremenek/swift,xwu/swift,lorentey/swift,nathawes/swift,apple/swift,tkremenek/swift,nathawes/swift,stephentyrone/swift,karwa/swift,airspeedswift/swift,hooman/swift,stephentyrone/swift,ahoppen/swift,nathawes/swift,shajrawi/swift,parkera/swift,lorentey/swift,jmgc/swift,hooman/swift,airspeedswift/swift,ahoppen/swift,lorentey/swift,parkera/swift,CodaFi/swift