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/string.cons/char_assignment.pass.cpp

@@ -14,7 +14,6 @@
 #include <string>
 #include <cassert>
 
-#include "test_macros.h"
 #include "min_allocator.h"
 
 template <class S>
@@ -23,7 +22,7 @@ test(S s1, typename S::value_type s2)
 {
     typedef typename S::traits_type T;
     s1 = s2;
-    LIBCPP_ASSERT(s1.__invariants());
+    assert(s1.__invariants());
     assert(s1.size() == 1);
     assert(T::eq(s1[0], s2));
     assert(s1.capacity() >= s1.size());
@@ -38,7 +37,7 @@ int main()
     test(S("123456789"), 'a');
     test(S("1234567890123456789012345678901234567890123456789012345678901234567890"), 'a');
     }
-#if TEST_STD_VER >= 11
+#if __cplusplus >= 201103L
     {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S(), 'a');