[NFC] Add PrettyStackTraces to ObjC forward decls
[NFC] Add PrettyStackTraces to ObjC forward decls

Helps identify the cause of some crashes.

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