Revert "Do not print package-name in non-package interface by default."

include/swift/Frontend/ModuleInterfaceSupport.h

@@ -70,6 +70,10 @@ struct ModuleInterfaceOptions {
   /// Print imports that are missing from the source and used in API.
   bool PrintMissingImports = true;
 
+  /// If true, package-name flag is not printed in either public or private
+  /// interface file.
+  bool DisablePackageNameForNonPackageInterface = false;
+
   /// Intentionally print invalid syntax into the file.
   bool DebugPrintInvalidSyntax = false;