Special-case catalyst when computing a path for stdlib_dir in lit config target_sdk_name is `macosx` when targeting `maccatalyst`, but the stdlib swift modules are placed under `swift/maccatalyst` instead of `swift/macosx`. Using `run_os` is not correct in the general sense though, hence the requirement for a special case instead of just replacing `target_sdk_name` with it. For example, it would be invalid to use run_os instead of target_sdk_name on Windows, because the sdk_name is going to be windows while the run_os variable may be windows-msvc.
Special-case catalyst when computing a path for stdlib_dir in lit config
target_sdk_name is `macosx` when targeting `maccatalyst`, but the stdlib swift modules are placed under `swift/maccatalyst` instead of `swift/macosx`.
Using `run_os` is not correct in the general sense though, hence the requirement for a special case instead of just replacing `target_sdk_name` with it.
For example, it would be invalid to use run_os instead of target_sdk_name on Windows, because the sdk_name is going to be windows while the run_os variable may be windows-msvc.

ahoppen/swift,airspeedswift/swift,tkremenek/swift,benlangmuir/swift,allevato/swift,xwu/swift,xwu/swift,ahoppen/swift,glessard/swift,benlangmuir/swift,tkremenek/swift,allevato/swift,jckarter/swift,benlangmuir/swift,roambotics/swift,gregomni/swift,nathawes/swift,tkremenek/swift,ahoppen/swift,gregomni/swift,parkera/swift,JGiola/swift,rudkx/swift,benlangmuir/swift,CodaFi/swift,benlangmuir/swift,hooman/swift,nathawes/swift,atrick/swift,apple/swift,allevato/swift,jmgc/swift,hooman/swift,nathawes/swift,airspeedswift/swift,glessard/swift,apple/swift,rudkx/swift,ahoppen/swift,hooman/swift,jckarter/swift,hooman/swift,allevato/swift,hooman/swift,jmgc/swift,nathawes/swift,xwu/swift,jckarter/swift,airspeedswift/swift,airspeedswift/swift,xwu/swift,nathawes/swift,rudkx/swift,glessard/swift,airspeedswift/swift,rudkx/swift,gregomni/swift,nathawes/swift,jmgc/swift,roambotics/swift,parkera/swift,CodaFi/swift,parkera/swift,jmgc/swift,jmgc/swift,xwu/swift,CodaFi/swift,jmgc/swift,allevato/swift,atrick/swift,parkera/swift,jmgc/swift,tkremenek/swift,gregomni/swift,allevato/swift,jckarter/swift,jckarter/swift,jckarter/swift,CodaFi/swift,atrick/swift,ahoppen/swift,glessard/swift,gregomni/swift,allevato/swift,JGiola/swift,apple/swift,rudkx/swift,parkera/swift,roambotics/swift,apple/swift,tkremenek/swift,rudkx/swift,benlangmuir/swift,tkremenek/swift,xwu/swift,airspeedswift/swift,parkera/swift,JGiola/swift,apple/swift,JGiola/swift,roambotics/swift,roambotics/swift,atrick/swift,CodaFi/swift,JGiola/swift,jckarter/swift,CodaFi/swift,ahoppen/swift,roambotics/swift,apple/swift,gregomni/swift,glessard/swift,airspeedswift/swift,atrick/swift,atrick/swift,CodaFi/swift,hooman/swift,parkera/swift,parkera/swift,xwu/swift,JGiola/swift,glessard/swift,hooman/swift,tkremenek/swift,nathawes/swift