Demangler: Fix out-of-bounds read printing quoted high-bit characters.
Demangler: Fix out-of-bounds read printing quoted high-bit characters.

If `char` is signed, then `c >> 4` produces a signed negative number when `c` has the high bit
set, and `Hexdigit[c >> 4]` reads junk out of the memory right before `Hexdigit`. Change the code
here to use `unsigned char`.

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