We can now IRgen references to single-token macros that have integral
or floating literals. They map to CInt and CDouble,
respectively. There is more work to do here, later.
Swift SVN r3958
When doing name lookup into a Clang module, look for a macro with the given name and try to convert it into a Swift decl. Turn simple literal macros with expansions <number>, -<number>, or (-<number>) into Swift read-only properties. Map integer literals to Swift 'Int' and float literals to Swift 'Double' for want of a better type to map them to--it would probably be better if we had a decl that behaved like Pascal 'const' and converted like a literal value. Codegen for the synthesized properties isn't wired up, so compiling code that tries to use macro values will currently die because of missing externals.
Swift SVN r3941
