[stdlib] Further simplify string-to-integer parsing and change some inlining choices.
[stdlib] Further simplify string-to-integer parsing and change some inlining choices.

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