Revert "tests: temporarily disable Runtime/linux-fatal-backtrace.swift"
Revert "tests: temporarily disable Runtime/linux-fatal-backtrace.swift"

This reverts commit aed0d91fc9d1110b801f362afc68cf60dd4927a1.

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