[libcxx] Adjust trivial_abi tests for C++03 and C++11 testing

This change replaces std::make_unique with manual construction of
std::unique_ptr to make the tests compatible with C++11
(std::make_unique is a C++14 feature).

libc++ supports std::unique_ptr and std::shared_ptr even in C++03 but
with some limitations: unique_ptr_array.pass.cpp and
shared_ptr_arg.pass.cpp fail to compile in C++03 mode and need to be
disabled.

Differential Revision: https://reviews.llvm.org/D84394

libcxx/test/libcxx/memory/trivial_abi/shared_ptr_arg.pass.cpp

@@ -14,6 +14,7 @@
 
 // There were assertion failures in both parse and codegen, which are fixed in clang 11.
 // UNSUPPORTED: gcc, clang-4, clang-5, clang-6, clang-7, clang-8, clang-9, clang-10
+// UNSUPPORTED: c++03
 
 #include <memory>
 #include <cassert>

libcxx/test/libcxx/memory/trivial_abi/unique_ptr_arg.pass.cpp

@@ -45,7 +45,7 @@ int main(int, char**) {
   //
   // With trivial-abi, expect_1 will see shared == 1 because shared_val is
   // incremented before get_val returns.
-  expect_1(&shared, get_val(std::make_unique<Node>(&shared)));
+  expect_1(&shared, get_val(std::unique_ptr<Node>(new Node(&shared))));
 
   // Check that the shared-value is still 1.
   expect_1(&shared, true);

libcxx/test/libcxx/memory/trivial_abi/unique_ptr_array.pass.cpp

@@ -14,6 +14,7 @@
 
 // There were assertion failures in both parse and codegen, which are fixed in clang 11.
 // UNSUPPORTED: gcc, clang-4, clang-5, clang-6, clang-7, clang-8, clang-9, clang-10
+// UNSUPPORTED: c++03
 
 #include <memory>
 #include <cassert>

libcxx/test/libcxx/memory/trivial_abi/unique_ptr_destruction_order.pass.cpp

@@ -53,7 +53,7 @@ int main(int, char**) {
   char shared_buf[3] = {'0', '0', '0'};
   int cur_idx = 0;
 
-  func(A(shared_buf, &cur_idx), std::make_unique<B>(shared_buf, &cur_idx),
+  func(A(shared_buf, &cur_idx), std::unique_ptr<B>(new B(shared_buf, &cur_idx)),
        C(shared_buf, &cur_idx));
 
   // With trivial_abi, the std::unique_ptr<B> arg is always destructed first.

libcxx/test/libcxx/memory/trivial_abi/unique_ptr_ret.pass.cpp

@@ -28,7 +28,7 @@ struct Node {
 __attribute__((noinline)) std::unique_ptr<Node> make_val(void** local_addr) {
   call_something();
 
-  auto ret = std::make_unique<Node>();
+  auto ret = std::unique_ptr<Node>(new Node);
 
   // Capture the local address of ret.
   *local_addr = &ret;