[nfc] Remove unneeded void cast of clangDC.
[nfc] Remove unneeded void cast of clangDC.

This is just a simple cleanup.

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