build: repair Windows build
build: repair Windows build

`-ivfsoverlay` is no longer passed through to the driver with
`clang-cl`.  Explicitly mark it as a clang option to ensure that the
option is handled properly.  This repairs the build on Windows.

hooman/swift,jckarter/swift,ahoppen/swift,harlanhaskins/swift,atrick/swift,jmgc/swift,rudkx/swift,danielmartin/swift,CodaFi/swift,jopamer/swift,karwa/swift,amraboelela/swift,parkera/swift,hooman/swift,jckarter/swift,gregomni/swift,xedin/swift,sschiau/swift,devincoughlin/swift,apple/swift,karwa/swift,danielmartin/swift,stephentyrone/swift,alblue/swift,hooman/swift,lorentey/swift,xwu/swift,karwa/swift,CodaFi/swift,brentdax/swift,airspeedswift/swift,jopamer/swift,allevato/swift,CodaFi/swift,airspeedswift/swift,hooman/swift,sschiau/swift,rudkx/swift,amraboelela/swift,stephentyrone/swift,stephentyrone/swift,roambotics/swift,alblue/swift,JGiola/swift,shajrawi/swift,gregomni/swift,gribozavr/swift,airspeedswift/swift,xedin/swift,atrick/swift,benlangmuir/swift,apple/swift,roambotics/swift,nathawes/swift,shahmishal/swift,stephentyrone/swift,huonw/swift,benlangmuir/swift,austinzheng/swift,rudkx/swift,alblue/swift,nathawes/swift,lorentey/swift,aschwaighofer/swift,harlanhaskins/swift,devincoughlin/swift,karwa/swift,harlanhaskins/swift,lorentey/swift,huonw/swift,austinzheng/swift,jopamer/swift,xwu/swift,shahmishal/swift,jmgc/swift,benlangmuir/swift,jckarter/swift,lorentey/swift,huonw/swift,xedin/swift,jckarter/swift,danielmartin/swift,natecook1000/swift,jckarter/swift,jmgc/swift,amraboelela/swift,practicalswift/swift,gribozavr/swift,airspeedswift/swift,gregomni/swift,shahmishal/swift,practicalswift/swift,brentdax/swift,gribozavr/swift,harlanhaskins/swift,JGiola/swift,austinzheng/swift,JGiola/swift,amraboelela/swift,nathawes/swift,ahoppen/swift,danielmartin/swift,JGiola/swift,shahmishal/swift,jmgc/swift,parkera/swift,parkera/swift,jckarter/swift,tkremenek/swift,harlanhaskins/swift,devincoughlin/swift,benlangmuir/swift,huonw/swift,natecook1000/swift,CodaFi/swift,allevato/swift,jmgc/swift,parkera/swift,sschiau/swift,atrick/swift,xwu/swift,sschiau/swift,tkremenek/swift,tkremenek/swift,jckarter/swift,gribozavr/swift,hooman/swift,jopamer/swift,xedin/swift,alblue/swift,tkremenek/swift,parkera/swift,shahmishal/swift,karwa/swift,nathawes/swift,nathawes/swift,parkera/swift,lorentey/swift,allevato/swift,glessard/swift,nathawes/swift,natecook1000/swift,shajrawi/swift,lorentey/swift,huonw/swift,atrick/swift,airspeedswift/swift,danielmartin/swift,brentdax/swift,harlanhaskins/swift,CodaFi/swift,roambotics/swift,jopamer/swift,parkera/swift,sschiau/swift,CodaFi/swift,sschiau/swift,rudkx/swift,devincoughlin/swift,JGiola/swift,xedin/swift,practicalswift/swift,huonw/swift,lorentey/swift,atrick/swift,devincoughlin/swift,brentdax/swift,stephentyrone/swift,JGiola/swift,shahmishal/swift,shajrawi/swift,shajrawi/swift,austinzheng/swift,aschwaighofer/swift,xedin/swift,xedin/swift,stephentyrone/swift,alblue/swift,lorentey/swift,benlangmuir/swift,tkremenek/swift,shajrawi/swift,shajrawi/swift,allevato/swift,shajrawi/swift,aschwaighofer/swift,devincoughlin/swift,aschwaighofer/swift,glessard/swift,glessard/swift,amraboelela/swift,glessard/swift,devincoughlin/swift,ahoppen/swift,alblue/swift,gregomni/swift,practicalswift/swift,roambotics/swift,apple/swift,xwu/swift,aschwaighofer/swift,brentdax/swift,rudkx/swift,harlanhaskins/swift,stephentyrone/swift,danielmartin/swift,practicalswift/swift,allevato/swift,tkremenek/swift,gribozavr/swift,gregomni/swift,atrick/swift,devincoughlin/swift,practicalswift/swift,ahoppen/swift,gregomni/swift,jopamer/swift,apple/swift,austinzheng/swift,natecook1000/swift,xwu/swift,allevato/swift,roambotics/swift,huonw/swift,jmgc/swift,apple/swift,alblue/swift,austinzheng/swift,aschwaighofer/swift,roambotics/swift,benlangmuir/swift,aschwaighofer/swift,amraboelela/swift,practicalswift/swift,brentdax/swift,sschiau/swift,austinzheng/swift,shahmishal/swift,shajrawi/swift,sschiau/swift,brentdax/swift,parkera/swift,xwu/swift,rudkx/swift,practicalswift/swift,gribozavr/swift,amraboelela/swift,airspeedswift/swift,gribozavr/swift,nathawes/swift,hooman/swift,danielmartin/swift,apple/swift,natecook1000/swift,natecook1000/swift,xwu/swift,karwa/swift,CodaFi/swift,glessard/swift,airspeedswift/swift,jopamer/swift,glessard/swift,karwa/swift,ahoppen/swift,natecook1000/swift,allevato/swift,shahmishal/swift,jmgc/swift,karwa/swift,gribozavr/swift,tkremenek/swift,hooman/swift,ahoppen/swift,xedin/swift