pschuh's proposed fix to C++ importer test breakages

Author: Eugene Burmako

lib/ClangImporter/ImportDecl.cpp

@@ -8060,7 +8060,7 @@ ClangImporter::Implementation::importDeclContextOf(
   switch (context.getKind()) {
   case EffectiveClangContext::DeclContext: {
     auto dc = context.getAsDeclContext();
-    if (dc->isFileContext()) {
+    if (dc->isTranslationUnit()) {
       if (auto *module = getClangModuleForDecl(decl))
         return module;
       else