[AST] Support SILFunctionType/SILBlockStorageType in ClangTypeConverter.
[AST] Support SILFunctionType/SILBlockStorageType in ClangTypeConverter.

This is needed before we can store Clang types in SILFunctionType.

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