Revert "[stdlib] AutoreleasingUnsafeMutablePointer: Switch subscripts to _read accessors"
Revert "[stdlib] AutoreleasingUnsafeMutablePointer: Switch subscripts to _read accessors"

This was an ABI break, since it didn't make it into 5.0. Using _read here is unimportant, so we're just going to revert rather than try being fancy.

This reverts commit 04586e39163c532fa09f1d71d1aa0b35ffa92140.

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