[libcxx] Fix deprecation warning by suppressing deprecated around __test_has_construct

[zoecarver]

Summary

In C++17 some tests started failing after a521532aa16df2c06c91488f2a4e787586f0a611. This fixes those errors by suppressing the deprecation warning when calling construct in __test_has_construct. This is the same solution as __has_destroy_test already uses.

[zoecarver]

I'm going to commit this to fix the bots. If it would be better to revert both commits, let me know and I'll do that instead.

[ldionne]

Post-commit: this LGTM, thanks for fixing.

libcxx/include/memory

 template <class _Alloc, class _SizeType, class _ConstVoidPtr>
 struct __has_allocate_hint
     : true_type
 {
 };
 
 #endif  // _LIBCPP_CXX03_LANG
 
+_LIBCPP_SUPPRESS_DEPRECATED_PUSH
 template <class _Alloc, class ..._Args,
     class = decltype(_VSTD::declval<_Alloc>().construct(_VSTD::declval<_Args>()...))>
 static true_type __test_has_construct(int);
+_LIBCPP_SUPPRESS_DEPRECATED_POP
+
 template <class _Alloc, class...>
 static false_type __test_has_construct(...);
 
 template <class _Alloc, class ..._Args>
 struct __has_construct : decltype(__test_has_construct<_Alloc, _Args...>(0)) {};
 
 #if !defined(_LIBCPP_CXX03_LANG)