Revert "Update aosp/master libcxx rebase to r263688"

The world is burning.

This reverts commit c004fd909c, reversing
changes made to 1418e4163d.

test/std/strings/basic.string/allocator_mismatch.fail.cpp

@@ -1,18 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-// <string>
-//   The container's value type must be the same as the allocator's value type
-
-#include <string>
-
-int main()
-{
-    std::basic_string<char, std::char_traits<char>, std::allocator<int> > s;
-}