swift234

ClangImporter: Groundwork for importing #defines.

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