Revert "Revert "Update aosp/master libcxx rebase to r263688""

This reverts commit 1d4a1edbc7.

Change-Id: I2909937fe582f2c5552bc86e7f4d2d5cff0de0aa

test/libcxx/containers/gnu_cxx/hash_set.pass.cpp

@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+#include <ext/hash_set>
+
+namespace __gnu_cxx {
+template class hash_set<int>;
+}
+
+int main() {
+  typedef __gnu_cxx::hash_set<int> Set;
+  Set s;
+  Set s2(s);
+  ((void)s2);
+}