[PrintOptions] Enable EnumRawValueMode::PrintObjCOnly for when generating interfaces for user consumption and for doc-support

rdar://17934156

Author: akyrtzi

include/swift/AST/PrintOptions.h

@@ -487,6 +487,7 @@ struct PrintOptions {
         QualifyNestedDeclarations::Always;
     result.PrintDocumentationComments = true;
     result.SkipUnderscoredKeywords = true;
+    result.EnumRawValues = EnumRawValueMode::PrintObjCOnly;
     return result;
   }