More clang support for darwin tls. Add a __has_feature macro and

target specific preprocessor define as well.

llvm-svn: 106715

clang/lib/Frontend/InitPreprocessor.cpp

@@ -460,6 +460,10 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   if (FEOpts.ProgramAction == frontend::RunAnalysis)
     Builder.defineMacro("__clang_analyzer__");
 
+  // Define __HAS_TLS__ if the target supports it.
+  if (TI.isTLSSupported())
+    Builder.defineMacro("__HAS_TLS__");
+  
   // Get other target #defines.
   TI.getTargetDefines(LangOpts, Builder);
 }