[benchmark] Add autoreleasepools to the Codable tests to prevent "leaks".
[benchmark] Add autoreleasepools to the Codable tests to prevent "leaks".

This was caught by the runtime leak checker.

rdar://47241432

tkremenek/swift,glessard/swift,allevato/swift,nathawes/swift,aschwaighofer/swift,stephentyrone/swift,apple/swift,glessard/swift,benlangmuir/swift,practicalswift/swift,jckarter/swift,hooman/swift,harlanhaskins/swift,shajrawi/swift,benlangmuir/swift,ahoppen/swift,sschiau/swift,devincoughlin/swift,allevato/swift,ahoppen/swift,parkera/swift,gregomni/swift,xedin/swift,roambotics/swift,sschiau/swift,roambotics/swift,JGiola/swift,sschiau/swift,shahmishal/swift,airspeedswift/swift,devincoughlin/swift,karwa/swift,karwa/swift,stephentyrone/swift,glessard/swift,devincoughlin/swift,rudkx/swift,rudkx/swift,xedin/swift,apple/swift,amraboelela/swift,shajrawi/swift,gribozavr/swift,aschwaighofer/swift,shajrawi/swift,allevato/swift,aschwaighofer/swift,practicalswift/swift,ahoppen/swift,practicalswift/swift,karwa/swift,gribozavr/swift,hooman/swift,glessard/swift,nathawes/swift,parkera/swift,ahoppen/swift,sschiau/swift,xedin/swift,shajrawi/swift,sschiau/swift,CodaFi/swift,harlanhaskins/swift,benlangmuir/swift,gregomni/swift,gribozavr/swift,allevato/swift,ahoppen/swift,CodaFi/swift,shajrawi/swift,lorentey/swift,jckarter/swift,shahmishal/swift,jmgc/swift,practicalswift/swift,tkremenek/swift,devincoughlin/swift,xedin/swift,airspeedswift/swift,roambotics/swift,atrick/swift,gribozavr/swift,aschwaighofer/swift,hooman/swift,allevato/swift,atrick/swift,tkremenek/swift,shahmishal/swift,CodaFi/swift,lorentey/swift,jckarter/swift,rudkx/swift,jckarter/swift,gregomni/swift,xwu/swift,xwu/swift,shahmishal/swift,xwu/swift,harlanhaskins/swift,atrick/swift,nathawes/swift,gribozavr/swift,shajrawi/swift,xedin/swift,devincoughlin/swift,stephentyrone/swift,aschwaighofer/swift,benlangmuir/swift,apple/swift,lorentey/swift,CodaFi/swift,stephentyrone/swift,rudkx/swift,amraboelela/swift,nathawes/swift,sschiau/swift,JGiola/swift,allevato/swift,gregomni/swift,rudkx/swift,gregomni/swift,parkera/swift,jckarter/swift,harlanhaskins/swift,stephentyrone/swift,benlangmuir/swift,sschiau/swift,airspeedswift/swift,glessard/swift,apple/swift,lorentey/swift,devincoughlin/swift,xedin/swift,parkera/swift,CodaFi/swift,amraboelela/swift,nathawes/swift,CodaFi/swift,xedin/swift,xwu/swift,ahoppen/swift,roambotics/swift,tkremenek/swift,JGiola/swift,gregomni/swift,lorentey/swift,parkera/swift,sschiau/swift,jmgc/swift,hooman/swift,amraboelela/swift,lorentey/swift,xedin/swift,xwu/swift,airspeedswift/swift,aschwaighofer/swift,xwu/swift,gribozavr/swift,JGiola/swift,apple/swift,amraboelela/swift,karwa/swift,shahmishal/swift,devincoughlin/swift,JGiola/swift,jmgc/swift,aschwaighofer/swift,parkera/swift,tkremenek/swift,karwa/swift,airspeedswift/swift,benlangmuir/swift,rudkx/swift,nathawes/swift,atrick/swift,apple/swift,devincoughlin/swift,hooman/swift,gribozavr/swift,amraboelela/swift,shahmishal/swift,stephentyrone/swift,tkremenek/swift,shajrawi/swift,jckarter/swift,atrick/swift,hooman/swift,karwa/swift,atrick/swift,gribozavr/swift,shahmishal/swift,hooman/swift,airspeedswift/swift,amraboelela/swift,xwu/swift,karwa/swift,practicalswift/swift,JGiola/swift,practicalswift/swift,harlanhaskins/swift,practicalswift/swift,roambotics/swift,harlanhaskins/swift,stephentyrone/swift,jckarter/swift,parkera/swift,lorentey/swift,shahmishal/swift,parkera/swift,glessard/swift,lorentey/swift,jmgc/swift,allevato/swift,shajrawi/swift,harlanhaskins/swift,jmgc/swift,tkremenek/swift,roambotics/swift,practicalswift/swift,karwa/swift,CodaFi/swift,jmgc/swift,jmgc/swift,nathawes/swift,airspeedswift/swift