[IRGen/Reflection] Emit built-in reflection metadata in JIT mode

Since Mirrors are using swift_getFieldAt we need built-in type
metadata present in JIT/REPL mode as well, otherwise some of the
types are going to become unprintable.

Author: xedin

lib/IRGen/IRGen.cpp

@@ -767,6 +767,7 @@ static std::unique_ptr<llvm::Module> performIRGeneration(IRGenOptions &Opts,
 
     // Register our info with the runtime if needed.
     if (Opts.UseJIT) {
+      IGM.emitBuiltinReflectionMetadata();
       IGM.emitRuntimeRegistration();
     } else {
       // Emit protocol conformances into a section we can recognize at runtime.