Add test cases for IRGen poison emission.
Add test cases for IRGen poison emission.

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