[libc++] Fix atomic test for _BitInt

[ldionne]

Summary

In 6c75ab5f66b4, Clang deprecated _ExtInt in favor of _BitInt, which
made this test fail. This patch disables the test on older compilers
and uses the new _BitInt type instead.

[aaron.ballman]

LGTM! Thanks for catching this!

[ldionne]

Try to fix CI

[uabelho]

I've verified this patch solves problems we see in our downstream CI with
https://reviews.llvm.org/rG6c75ab5f66b403f7ca67e86aeed3a58abe10570b

Please submit :)

libcxx/test/libcxx/atomics/bit-int.verify.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <atomic>
 
-// Make sure that `std::atomic` doesn't work with `_ExtInt`. The intent is to
+// Make sure that `std::atomic` doesn't work with `_BitInt`. The intent is to
 // disable them for now until their behavior can be designed better later.
 // See https://reviews.llvm.org/D84049 for details.
 
-// UNSUPPORTED: apple-clang-12
+// TODO(ldionne): Re-enable the test on clang-14 once 6c75ab5f66b4 lands in the CI.
+// UNSUPPORTED: apple-clang-12, apple-clang-13
+// UNSUPPORTED: clang-12, clang-13, clang-14
 
 // UNSUPPORTED: c++03
 
 #include <atomic>
 
 int main(int, char**)
 {
-  // expected-error@atomic:*1 {{_Atomic cannot be applied to integer type '_ExtInt(32)'}}
-  std::atomic<_ExtInt(32)> x(42);
+  // expected-error@atomic:*1 {{_Atomic cannot be applied to integer type '_BitInt(32)'}}
+  std::atomic<_BitInt(32)> x(42);
 
   return 0;
 }