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/copy_assignment.pass.cpp

@@ -15,7 +15,6 @@
 #include <string>
 #include <cassert>
 
-#include "test_macros.h"
 #include "min_allocator.h"
 
 template <class S>
@@ -23,7 +22,7 @@ void
 test(S s1, const S& s2)
 {
     s1 = s2;
-    LIBCPP_ASSERT(s1.__invariants());
+    assert(s1.__invariants());
     assert(s1 == s2);
     assert(s1.capacity() >= s1.size());
 }
@@ -48,7 +47,7 @@ int main()
            "1234567890123456789012345678901234567890123456789012345678901234567890"),
          S("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz"));
     }
-#if TEST_STD_VER >= 11
+#if __cplusplus >= 201103L
     {
     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
     test(S(), S());