[libcxx] Fix buildbots on Debian

Debian build bots are running Clang 4, which apparently does not support
the "deprecated" attribute properly. Clang pretends to support the attribute,
but the attribute doesn't do anything.

(live example: https://wandbox.org/permlink/0De69aXns0t1D59r)

On a separate note, I'm not sure I understand why we're even running the
libc++ tests under Clang-4. Is this a configuration we support? I can
understand that libc++ should _build_ with Clang 4, but it's not clear
to me that new libc++ headers should be usable under older compilers
like that.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@342854 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/algorithms/alg.modifying.operations/alg.random.shuffle/random_shuffle.depr_in_cxx14.fail.cpp

@@ -18,6 +18,7 @@
 //     random_shuffle(RandomAccessIterator first, RandomAccessIterator last,
 //                    RandomNumberGenerator& rand);
 
+// UNSUPPORTED: clang-4.0
 // REQUIRES: verify-support
 
 // MODULES_DEFINES: _LIBCPP_ENABLE_DEPRECATION_WARNINGS

test/libcxx/depr/depr.auto.ptr/auto.ptr/auto_ptr.depr_in_cxx11.fail.cpp

@@ -19,6 +19,7 @@
 //
 // Deprecated in C++11
 
+// UNSUPPORTED: clang-4.0
 // REQUIRES: verify-support
 
 // MODULES_DEFINES: _LIBCPP_ENABLE_DEPRECATION_WARNINGS

test/libcxx/depr/depr.function.objects/adaptors.depr_in_cxx11.fail.cpp

@@ -9,6 +9,7 @@
 
 // <functional>
 
+// UNSUPPORTED: clang-4.0
 // REQUIRES: verify-support
 
 // MODULES_DEFINES: _LIBCPP_ENABLE_DEPRECATION_WARNINGS