[TBD] Validate TBDs in debug compilers for all platforms.
[TBD] Validate TBDs in debug compilers for all platforms.

This is generalizing caa3dd4d291ec93c1a59f1db62604e703bff8468 to work even on
non-Apple platforms.

Fixes rdar://problem/40431434.

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