Predefine IB_DESIGNABLE and IBInspectable macros. <rdar://problem/17441860>

These macros are used as markers for Interface Builder and need to be defined
to empty strings since they have no impact on the code.

Patch by Ted Kremenek.

llvm-svn: 215259

clang/lib/Frontend/InitPreprocessor.cpp

@@ -530,6 +530,8 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
     Builder.defineMacro("IBOutletCollection(ClassName)",
                         "__attribute__((iboutletcollection(ClassName)))");
     Builder.defineMacro("IBAction", "void)__attribute__((ibaction)");
+    Builder.defineMacro("IBInspectable", "");
+    Builder.defineMacro("IB_DESIGNABLE", "");
   }
 
   if (LangOpts.CPlusPlus)