Fix bug #27260 - add missing swap(reference, reference) to vector<bool>.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@265672 91177308-0d34-0410-b5e6-96231b3b80d8

include/vector

@@ -2363,6 +2363,7 @@ public:
         _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || 
                     __is_nothrow_swappable<allocator_type>::value);
 #endif
+    static void swap(reference __x, reference __y) _NOEXCEPT { _VSTD::swap(__x, __y); }
 
     void resize(size_type __sz, value_type __x = false);
     void flip() _NOEXCEPT;