[Test] Added missing flag to Interpreter/rdar80847020.swift.
[Test] Added missing flag to Interpreter/rdar80847020.swift.

As of https://github.com/apple/swift/pull/38510 -Xfrontend
-disable-availability-checking is needed.

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