Fix for LWG Issue 2059: C++0x ambiguity problem with map::erase

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@236950 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/unordered_set b/include/unordered_set
index d06629f..26ef6fd 100644
--- a/include/unordered_set
+++ b/include/unordered_set
@@ -114,6 +114,7 @@
     void insert(initializer_list<value_type>);
 
     iterator erase(const_iterator position);
+    iterator erase(iterator position);  // C++14
     size_type erase(const key_type& k);
     iterator erase(const_iterator first, const_iterator last);
     void clear() noexcept;
@@ -263,6 +264,7 @@
     void insert(initializer_list<value_type>);
 
     iterator erase(const_iterator position);
+    iterator erase(iterator position);  // C++14
     size_type erase(const key_type& k);
     iterator erase(const_iterator first, const_iterator last);
     void clear() noexcept;