[libc++][test] Fix FreeBSD build

Author: emaste

libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_implicit_lifetime.pass.cpp

@@ -226,7 +226,9 @@ constexpr bool test() {
 
 #ifdef _LIBCPP_VERSION
   // These types should be implicit-lifetime, but they are not guaranteed to be so.
+#  ifndef _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
   test_is_implicit_lifetime<std::pair<int, float>>();
+#  endif
   test_is_implicit_lifetime<std::tuple<int, float>>();
 #endif