Change a couple ifdefs from '#if __cplusplus >= 2011xxx' to '#ifndef _LIBCPP_CXX03_LANG'. No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@275787 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/unordered_map b/include/unordered_map
index 319c71e..bf64ad6 100644
--- a/include/unordered_map
+++ b/include/unordered_map
@@ -865,7 +865,7 @@
     _LIBCPP_INLINE_VISIBILITY
     unordered_map& operator=(const unordered_map& __u)
     {
-#if __cplusplus >= 201103L
+#ifndef _LIBCPP_CXX03_LANG
         __table_ = __u.__table_;
 #else
         if (this != &__u) {
@@ -1619,7 +1619,7 @@
     _LIBCPP_INLINE_VISIBILITY
     unordered_multimap& operator=(const unordered_multimap& __u)
     {
-#if __cplusplus >= 201103L
+#ifndef _LIBCPP_CXX03_LANG
         __table_ = __u.__table_;
 #else
         if (this != &__u) {